1. Make streusel: Mix flour, sugar and cinnamon in a large bowl. Use a pastry blender or fingertips to cut in butter until mixture forms pea-size crumbs.
2. Make cake: Preheat oven to 350°F; butter an 8-inch round baking pan.
3. In a bowl, mix flour with baking powder and salt. In a separate bowl, using an electric mixer on medium-high speed, beat butter and sugar until light. Beat in eggs one at a time. Reduce mixer speed to low and add flour mixture, alternating with milk and vanilla. Gently fold in cherries.
4. Spread batter in baking pan, sprinkle with streusel and bake until lightly browned on top and a toothpick inserted into center comes out clean, 50 to 55 minutes. Cool in pan on a wire rack for 10 minutes before serving.