Break white chocolate baking bars into pieces. Melt white chocolate and cream in a microwave-safe bowl at MEDIUM (50% power) 1 minute or until melted and smooth, stirring at 30-second intervals. (Do not overheat.) Let cool to room temperature (about 30 minutes). Beat butter and 1 cup powdered sugar at low speed with an electric mixer until blended. Add 5 cups powdered sugar alternately with almond liqueur, beating at low speed until blended after each addition. Add white chocolate mixture; beat at medium speed until spreading consistency.