In small bowl, mix flour, baking powder and salt; set aside. In large bowl, beat 1/2 cup butter and the granulated sugar with electric mixer on medium speed, scraping bowl occasionally, until fluffy. Add eggs one at a time, beating on high speed after each addition until smooth and blended. Add milk, liqueur, 1 teaspoon vanilla, the flour mixture and ground almonds; beat on medium speed until smooth. Stir in 6 ounces white chocolate. Spread batter in pan.