This isn't a typical muffin flavor, but it should be! Rhubarb muffins are super moist, which comes in part from the liquid in the rhubarb. Topped with a cinnamon and walnut crumble, this recipe is sure to feel like the epitome of spring!
Beat the egg and sugar until combined. Mix in buttermilk, cooled browned butter, and vanilla. Add flour, baking soda, baking powder, and salt. Mix until no streaks remain. Fold in rhubarb and ginger.
Fill greased muffin cups with approximately ¼ cup batter.
Prepare topping by mixing brown sugar, flour, cinnamon, and butter. Mix until the texture of wet sand. Add walnuts.
Top each muffin with crumble, about 1-2 tablespoons.
Place in oven and bake until the muffins dome and a wooden skewer comes out clean when pierced in the middle, about 16-22 minutes.
Remove from oven and cool in the pan for five minutes. Then remove and cool on a rack.