For Topping: COMBINE brown sugar, flour and cinnamon in small bowl; cut in butter until mixture resembles coarse crumbs. Stir in nuts.
For Coffee Cake: HEAT oven 375°F. Spray 9-inch square baking pan with no-stick cooking spray. Stir together flour, baking powder and salt in small bowl.
BEAT butter and sugar in large bowl until fluffy; beat in egg. On low speed, add milk alternately with flour mixture; blend well. Stir in mincemeat. Spread batter in prepared baking pan. Sprinkle with streusel topping.
BAKE 35 to 40 minutes or until toothpick inserted near center comes out clean. Serve warm.