Preheat the oven to 375°F. Chop the rhubarb into small pieces.
Add dry ingredients to a large bowl: whole wheat flour, all purpose flour, ground flaxseed, brown sugar, baking soda and salt. Mix together.
Add wet ingredients to a medium bowl: yogurt, beaten eggs, vegetable oil and vanilla extract. Mix together.
Make a well in the center of the dry ingredients, then pour the wet ingredients into the center. Fold the dry ingredients into the middle until muffin batter is evenly mixed.
Fold the chopped rhubarb into the muffin batter just until combined. Do not overmix.
Place paper liners into a muffin pan. Fill each muffin cup ¾ full. Bake for 18-22 minutes, or until tops are golden and a toothpick comes out clean when poked through the center.
Let cool 5 minutes, then transfer to a wire rack to cool completely. Serve and enjoy!
Recipe Notes:
Leftover rhubarb muffins can be stored in an airtight container on the counter or in the fridge for up to 3-4 days.
These muffins freeze beautifully. I prefer to wrap each one in parchment (or use plastic wrap) and add them to a freezer bag. Remove as much air as possible and seal tightly. These will keep fresh up to 6 months.
VARIATIONS: If rhubarb is too tart for you, consider reducing the rhubarb by half and adding fresh chopped strawberries to the batter.
Replace flours with whole wheat pastry flour. Yogurt can be replaced with 1 cup milk or 1 cup buttermilk. Try whole oats instead of ground flaxseed. Add in sunflower seeds or pumpkin seeds. For a heartier muffin, replace whole-wheat flour with whole spelt flour.
Chop the rhubarb into small pieces with a sharp knife. The smaller the better. No need to remove the fibrous skin.
Mix rhubarb well into batter so that it’s not clumped together. Clumped rhubarb won’t bake as well in the muffin batter. Freeze any leftover chopped rhubarb for future recipes.
Use an ice cream or cookie scoop to drop the batter into the muffin pan. If you don’t have one a spoon will work too. Fill each cup about ¾ full. Use paper muffin cups for easy clean-up.