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Chocolate Rhubarb Muffins With Lemon Zest Glaze

Chocolate Rhubarb Muffin with Lemon Zest

These chocolate rhubarb muffins with lemon zest glaze are a go-to recipe this time of year.  Rhubarb is one of the first harvests our raised-bed garden offers early in the growing season.  It’s jewel-toned stalks are also making an appearance at the farmer’s market and in grocery store produce aisles.  Traditionally, rhubarb’s sweet/tart flavor is matched up with strawberries for June pies and tarts  – but this chocolatey recipe adds a new twist to this seasonal gem.

Crumble Topping for Chocolate Rhubarb Muffins

The best part of this recipe is the ease in which it comes together.  There are three components:  the batter, a crumble topping, and a lemon zest glaze.  Each step is a simple, one-bowl mix that comes together in minutes. When all three are combined, however, the flavor is complex and sweetly satisfying.

Crumble Ingredients

Combine the following in a small bowl:

  • 1 tablespoon vegetable shortening
  • 1 tablespoon sugar
  • 2 tablespoons flour
  • 1 tablespoon unsweetened cocoa powder
  • 1/4 teaspoon salt
Using a fork, mash the sugar, flour, cocoa powder, and salt into the vegetable shortening until a uniform crumble forms.
Set this bowl aside and prepare the muffin batter.
Chocolate Rhubarb Muffin Crumble Topping Ingredients
Mashing Crumble Mixture for Chocolate Rhubarb Muffins

Batter for Chocolate Rhubarb Muffins

This batter recipe is a simple one-bowl wonder that only requires mixing with a spoon.  It is adapted from my chocolate vegan cupcake recipe but engineered a little differently to accommodate moisture from the rhubarb.  Start by mixing the dry ingredients.

Dry Ingredients
  • Place 1 1/4 cups of flour in a medium size mixing bowl
  • Add 1 cup of brown or white sugar
  • Add 1/3 cup of unsweetened cocoa powder
Flour and Mixing Bowl for Chocolate Rhubarb Muffins
Flour and Brown Sugar for chocolate Rhubarb Muffins

Additionally, you will need:

  • 1 teaspoon of baking powder
  • 1/2 teaspoon of salt

Combine all the ingredients in the mixing bowl, being careful to remove any lumps.  

The mixed dry ingredients for these chocolate rhubarb muffins should have a uniform color and texture before adding wet ingredients.

Baking Soda and Salt Spoons with Mixing Bowl
Mixing Bowl with Dry Ingredients for Chocolate Rhubarb Muffins
Adding Wet Ingredients
Now that the dry ingredients are blended in the mixing bowl you can:
  • Pour in 3/4 cup of warm, black coffee
  • 2 teaspoons of vanilla extract
  • 1/3 cup of vegetable oil
  • 1 teaspoon of white, apple cider or balsamic vinegar
Stir well, removing any lumps, until the batter is smooth.  You can use a whisk rather than a spoon if you find it works better for blending.  Once the batter comes together, add:
  • 1/4 cup chopped rhubarb
  • 1/4 cup semisweet chocolate chips
Wet Ingredients for Chocolate Rhubarb Muffins
Batter for Chocolate Rhubarb Muffins
Rhubarb and Chocolate Chips for Batter

Filling Tin with Chocolate Rhubarb Muffin Batter

You will need a muffin tin lined with muffin cups for this recipe.  I used tall, decorative cups, so this batch yielded 9 muffins.  If you used regular sized muffin cups, you should be able to fill a 12-cup muffin pan.  Alternately, the batter will fill a 9-inch loaf pan or one 8-inch cake pan depending on your preference.  If you choose a loaf or cake pan, you will have to watch carefully and adjust baking time.

I used a 1/4 cup measuring cup to scoop the batter and fill the cups.  Once all the cups are filled, you will cover the surface of the muffins with the crumble mixture you set aside.  Sprinkle evenly on tops until you have used all the crumble mixture.

Paper Muffin Cups in Muffin Pan
Chocolate Rhubarb Muffin Batter in Muffin Cups
Crumble on Raw Batter for Chocolate Rhubarb Muffins

Bake the chocolate rhubarb muffins in a preheated 350 degree oven for approximately 15 minutes.  Test with a toothpick before removing.  If the toothpick comes out clean, they are done.  

Place the hot muffin tin on a baking rack to cool.  As soon as you can handle the muffins, remove them from the tin and put them directly on the baking rack to finish cooling.

Baked Unglazed Chocolate Rhubarb Muffins

Glazing Chocolate Rhubarb Muffins

While the muffins are cooling, you can prepare the glaze.  This is also a simple, one-pan icing mix.

  • Melt two tablespoons of butter in a saucepan
  • Add 1 1/4 cups of powdered sugar 

Stir the mixture, adding a teaspoon of water at a time to thin the glaze to your desired consistency.  (Truly add only a tiny amount of water at a time.  A little goes a very long way.)  Thin until the glaze is loose enough to drizzle over the muffin tops.  It’s important not to let the glaze bubble at any point during the process or it will crystalize.  Just keep it warm and smooth.

  • Stir in the zest of a medium sized lemon

Drizzle the baked chocolate rhubarb muffins with lemon zest glaze.


Lemon Zest Glaze in Saucepan
Chocolate Rhubarb Muffin with Lemon Zest

Related Posts:

If you are interested the DIY vanilla infusion/extract I used in this recipe, follow this link.

I also have info on rhubarb in the garden.

And, my basic vegan chocolate cake recipe.

Chocolate Rhubarb Muffin with Lemon Zest

Chocolate Rhubarb Muffins with Lemon Zest Glaze

Prep Time 20 minutes
Cook Time 3 hours 20 minutes


  • 1 1/4 cups flour
  • 1 cup white or brown sugar
  • 1/3 cup unsweetened cocoa powder
  • 1 tsp baking soda
  • 1/2 tsp salt
  • 3/4 cup black coffee (warm)
  • 2 tsp vanilla extract
  • 1/3 cup vegetable oil
  • 1 tsp vinegar (white, apple cider, or balsamic)
  • 1/4 cup roughly chopped rhubarb
  • 1/4 cup semi-sweet chocolate chips

Chocolate Crumble Topping

  • 1 tbsp shortening
  • 2 tbsp flour
  • 1 tbsp cocoa powder
  • 1 tbsp sugar
  • 1/4 tsp salt

Lemon Zest Glaze

  • 2 tbsp butter
  • 1 1/4 cups powdered sugar
  • 1 zest of medium size lemon


  • Preheat oven to 350 degrees and set aside a muffin tin lined with paper muffin cups.
  • FOR CRUMBLE TOPPING, add shortening, flour, cocoa and salt to a small mixing bowl.
  • Using a fork, mash the dry ingredients into the shortening until an even crumble forms.
  • Set aside.
  • FOR CHOCOLATE RHUBARB MUFFIN BATTER, add flour, sugar, cocoa powder, baking soda and salt to a medium size mixing bowl.
  • Stir or whisk the dry ingredients together, removing any lumps and achieving an even color.
  • Add warm coffee, vanilla, vegetable oil and vinegar to the dry ingredients.
  • Stir until well blended.
  • Add chopped rhubarb and chocolate chips.
  • Stir until the rhubarb and chips are evenly distributed in the batter.
  • Scoop the batter into the paper muffin cups lining your muffin tin.
  • Retrieve the crumble mixture you set aside and sprinkle it evenly over the tops of all the muffins.
  • Place the filled muffin tin into a preheated 350 degree oven. Bake for 15-20 minutes depending on your oven. Check with a toothpick - if it comes out clean - the muffins are done.
  • Remove the muffin tin from the oven and transfer to a baking rack. When cool enough to handle, remove the muffin cups from the tin and place them on the baking rack to cool completely.
  • While the muffins are cooling, prep the LEMON ZEST GLAZE. You'll start by melting the butter in a small saucepan.
  • Stir in the powdered sugar. It will lump up. Add one teaspoon of water at a time until you reach a glaze consistency. A tiny amount of water goes a long way in thinning out this glaze. Keep the glaze warm, but do not let it bubble. When glaze feels like it is thin enough to drizzle onto muffins from a spoon, stir in the lemon zest.
  • Remove the saucepan from the heat and drizzle the glaze over the baked muffin tops. Work quickly, as the glaze will begin to solidify once off the heat.

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