Preheat oven to 350°F. Spray 9 in. springform pan and 8 x 2 in. square pan with vegetable pan spray.
In large bowl, prepare one brownie mix following package instructions. Spread into bottom of prepared square pan. In second large bowl, prepare remaining brownie mix following package instructions. Spread into prepared springform pan. Bake both pans together for 35-40 minutes or until toothpick inserted in center comes out clean. Cool completely. Turn oven down to 325°F.
Cut approximately half of the brownies from the square pan into 3/4 in. pieces (about 1 1/2 cups); set aside. Reserve remaining brownie for snacking.
For filling, beat cream cheese and sugar with electric mixer at medium speed in large bowl until smooth and creamy, about 5-10 minutes. Beat in sour cream and eggs. Add vanilla and almond extracts. When filling is smooth, gently stir in 1/2 cup of the cut brownies. Pour over cooled crust. Sprinkle remaining 1 cup cut brownies over cheesecake batter; lightly press into batter. Place cheesecake in middle of oven. Fill a large pan with hot water and place on rack underneath cheesecake.
Bake 1 hour 25 minutes or until cheesecake is firm on top but mixture is still jiggly when gently shaken. Turn off oven; leave cheesecake in closed oven 30 minutes to cool down slowly. Remove cheesecake from oven and cool on cooling grid 1 hour. Refrigerate covered at least 4 hours or overnight.
Makes about 12 servings.