1 cup all-purpose flour
1 1/4 teaspoon baking powder
1/4 teaspoon salt
1/2 teaspoon cinnamon (I added this)
6 tablespoons unsalted butter, softened
1/2 cup granulated sugar
2 large egg yolks
1 teaspoon vanilla extract
2/3 cup milk (I used skim)
1 cup sliced strawberries
2/3 cup finely chopped rhubarb
3/4 cup firmly packed brown sugar
1/2 cup all-purpose flour (I used 1/4 cup flour)
1/3 cup old fashioned oats (I added these)
1 teaspoon cinnamon (I added this) 5 tablespoons chilled unsalted butter, cut into small pieces (I only used 4 tablespoons)
Directions: Preheat oven to 350 degrees F. Grease and flour 1 (9-inch) round cake pan.
In a medium mixing bowl, sift together 1 cup flour, baking powder, salt, and cinnamon. In a large mixing bowl, beat together 6 tablespoons butter and granulated sugar until creamy, about 1 minute; beat in yolks and vanilla until combined. Gradually beat in flour mixture, alternating with milk until combined, about 1-2 minutes. Spread cake batter evenly into prepared pan. Top batter with strawberries and rhubarb. Bake for 20 minutes.
Meanwhile, prepare the crumb topping: Combine brown sugar, flour, oats, and 4 tablespoons butter; knead together using fingertips or a fork until well combined and mixture starts to clump together. Keep in freezer until ready for use. When cake has baked 20 minutes, top evenly with crumb mixture. Continue baking for an additional 15-20 minutes or until golden brown and a toothpick inserted into cakes comes out with moist crumbs attached. Cool for 30 minutes before running a knife around outside edges. Remove cake from pan and cool on a rack.