Preheat oven to 350 degrees F. Line 12 muffin cups with bake cups or lightly coat with nonstick cooking spray; set aside. In food processor finely grind nuts with 2 tablespoons sugar, 1/4 teaspoon salt, and cinnamon. Add 1 tablespoon orange juice; process until combined. Using a rounded teaspoon, shape some nut mixture into 12 balls; set aside remaining.

Combine flour, baking powder, and 1/4 teaspoons salt; set aside. beat butter with mixer 30 seconds; beat in 2/3 cup sugar. Beat in egg, orange juice, and milk on low until combined. Gradually add flour mixture; beat just until combined. Spoon half of batter into cups; top with walnut balls, pressing in lightly. Top with remaining batter. Bake about 20 minutes or until tops spring back when lightly touched. Cool in pans 5 minutes. Remover and cool on rack. Spread frosting; top with reserved nut mixture. Makes 12 muffins.

In bowl beat 1/3 cup softened butter, 1 tablespoon whipping cream, and 1/2 teaspoon finely shredded orange peel with mixer on low speed until just combined. Add 1-1/2 cups powdered sugar. Beat on medium speed until smooth. Makes about 1 cup.