Ingredients:

  • 1.5 cups all-purpose flour
  • 0.75 cup light brown sugar, packed
  • 1 tsp baking powder
  • 0.5 tsp baking soda
  • 0.25 tsp salt
  • 1 large egg
  • 0.5 cup full-fat sour cream
  • 4 tbsp unsalted butter, melted and cooled
  • 1 tsp pure vanilla extract
  • 1 cup fresh rhubarb, diced into 1/4-inch pieces
  • 3 tbsp all-purpose flour
  • 2 tbsp brown sugar
  • 1 tbsp cold unsalted butter, cubed

Instructions:

  1. Preheat the oven to 375°F (190°C) and line a 12-cup mini muffin tin with paper liners or grease with butter.
  2. In a medium mixing bowl, whisk together 1.5 cups all-purpose flour, 3/4 cup brown sugar, 1 tsp baking powder, 1/2 tsp baking soda, and 1/4 tsp salt until no lumps remain.
  3. In a second bowl, whisk together the egg, 1/2 cup sour cream, 4 tbsp melted butter, and 1 tsp vanilla extract until smooth and emulsified.
  4. Pour the wet ingredients into the dry ingredients and fold gently with a spatula until just combined; do not overmix.
  5. Gently fold in the 1 cup of diced rhubarb until evenly distributed.
  6. Divide the batter evenly among the 12 mini muffin cups.
  7. For the optional crumble, pinch together 3 tbsp flour, 2 tbsp brown sugar, and 1 tbsp cold cubed butter with your fingers and sprinkle on top of each muffin.
  8. Bake for 20 minutes or until the edges are golden-brown and a toothpick inserted into the center comes out clean.