These rhubarb muffins are soft, tender, and packed with fresh, tart flavor. They're easy to make, perfectly sweet, and a delicious way to celebrate rhubarb season.
Prepare the batter: Beat the egg and sugar until combined. Mix in buttermilk, cooled browned butter, and vanilla extract. Add flour, baking soda, baking powder, and salt. Mix until no streaks remain. Fold in the rhubarb. Place in the fridge overnight or until ready to use. If baking right away, allow to rest in the fridge for 30 minutes before baking.
1 large egg, 1 ¼ cups light brown sugar, 1 cup buttermilk, 8 tbsp (1 stick) browned unsalted butter, 1 tsp vanilla extract, 2 ½ cups all-purpose flour, 1 tsp baking soda, 1 tsp baking powder, ½ tsp kosher salt, 2 cups diced rhubarb
Prepare the topping: Mix the brown sugar, flour, cinnamon, and butter. Mix until the texture is like wet sand. Place in freezer, or until ready to use.
⅓ cup light brown sugar, ¼ cup all-purpose flour, 1 tsp ground cinnamon, 4 tbsp unsalted butter
Fill the pans: Fill greased jumbo muffin cups with approximately ½ cup batter. The batter should be split equally between 6 jumbo muffin cups. Top each muffin with crumble, about 2 tablespoons.
Bake: Place in the preheated 425°F oven and bake for 5 minutes. Then, turn the oven down to 350°F and continue baking until the muffins dome and a wooden skewer comes out clean when pierced in the middle, about 16-20 minutes. Remove from the oven and cool in the pan for 5 minutes. Then remove and cool on a rack.