Rhubarb Streusel Cakes

These cupcakes were my contribution to a pre-Memorial Day picnic this weekend. I love how tart rhubarb is, and I'm glad my friends did too.

(adapted from Gourmet)
makes 12 cupcakes

For topping:
1/2 cup all-purpose flour
1/3 cup packed brown sugar
1/4 teaspoon cinnamon
pinch of salt
2 tablespoons unsalted butter, softened
1/2 lb fresh rhubarb (about 3 stalks), cut into 1/4-inch dice
3 tablespoons confectioners sugar

For cake batter:
1 1/4 cups all-purpose flour
1 teaspoon baking powder
1 teaspoon salt
1 stick (1/2 cup) unsalted butter, softened
1/2 cup granulated sugar
2 large eggs
1/2 teaspoon vanilla
1/2 cup whole milk

Preheat oven to 375°F. Butter a 12-cup muffin pan, or line with paper muffin cups.

Make streusel for topping:
Whisk together flour, brown sugar, cinnamon, and salt in a bowl. Blend in butter with your fingertips until mixture forms small clumps.

Make batter:
Whisk together flour, baking powder, and salt in a bowl. Beat together butter and sugar in a large bowl until blended, about 2 minutes. Add eggs and vanilla and beat until fluffy, about 1 minute. Add flour mixture and milk alternately in 2 batches, beginning and ending with flour mixture and mixing until just combined.

Top and bake cakes:
Divide batter among muffin cups (each cup will be about half full). Toss rhubarb with confectioners sugar and sprinkle batter with rhubarb, then crumble streusel evenly on top. Bake in middle of oven until tops are golden and a tester inserted in center of a cake comes out clean, 22 to 25 minutes. Cool cakes in pan on a rack 3 minutes, then loosen edges of cakes with a small sharp knife or small metal spatula. Remove cakes from pan and put on rack to cool slightly.

Cakes keep in an airtight container at room temperature 3 days.