Preheat oven to 375°F. Prepare Delectovals Mini Cake Pan with vegetable pan spray.

In small bowl, sift together flour, baking powder and salt. In large bowl, whip egg whites with electric mixer until foamy. Add cream of tartar and whip until stiff but not dry. In clean bowl, whip egg yolks 1 minute; add vanilla and gradually add sugar, whipping until mixture is pale yellow and doubled in volume. With rubber spatula, fold 1/3 of egg whites into yolks to loosen; fold in remaining whites until nearly combined. Add flour and fold until no streaks remain. Fill cavities about 3/4 full with batter; smooth the tops.

Bake 6-8 minutes or until top is lightly browned and center springs back when touched. Cool in pan on cooling grid 5 minutes. Run a 9 in. spatula around edges of Delectovals to loosen. Remove from pan; cool completely.

In large bowl, beat butter and sugar until well combined, scraping down bottom and sides of bowl as necessary. Add vanilla and milk and beat until light and fluffy. Using Bismarck Tip #230, pipe filling into the bottom of Delectovals in 3 spots.