1. Preheat oven to 350 degrees F. Using two muffin pans, line 15 muffin cups with paper liners and spray liners with nonstick vegetable oil spray.
2. Make topping. In a medium bowl, use a large spoon to stir together flour, brown sugar, cinnamon, and salt. Add melted butter and continue stirring until crumbs form. Mix in white chocolate chips; set aside.
3. Make cupcakes. Sift cake flour, baking powder, and salt into a medium bowl. Set aside. In a large bowl, use an electric mixer on medium speed to beat butter and sugar until light and creamy, about 3 to 5 minutes. Beat in eggs one at a time. Mix in vanilla extract. On low speed, mix in half the flour mixture, then milk. Mix in remaining flour mixture, just to incorporate. Stir chopped rhubarb into batter.
4. Divide batter evenly among 15 lined muffin cups. Spoon a heaping Tbsp. of crumb topping over each cupcake. Press crumbs gently into batter.
5. Bake just until a toothpick inserted in center of cupcake comes out clean and edges are lightly browned, about 20 to 22 minutes.
6. Cool cupcakes for 10 minutes in pan on a wire rack. Transfer cupcakes in their paper liners to wire rack to cool completely, about 30 minutes. Serve at room temperature. Cupcakes can be covered and stored at room temperature for up to two days.
Source: Hannaford fresh Magazine, March - April 2007