Heat oven to 350°F. Grease bottom only of 13x9-inch pan with shortening; lightly flour. In 2-quart saucepan, cook and stir filling ingredients over medium-low heat until caramels are melted. Set aside.
In large bowl, beat cake ingredients with electric mixer on low speed 30 seconds. Beat on medium speed 2 minutes. Spread half of batter in pan. Bake 20 minutes. Spread filling over partially baked cake; cover with remaining batter. Bake 20 to 25 minutes or until toothpick inserted in center comes out clean. Cool completely.
In small bowl, beat 1/2 cup butter, the chocolate, half-and-half and vanilla with electric mixer on medium speed until well blended. Beat in powdered sugar until light and fluffy. Frost cooled cake; sprinkle with almonds.