For loaves: Place chopped pecans in a small dish. Pour 1/4 cup of Praline liqueur over nuts; stir to coat and set aside. While nuts are soaking in liqueur, preheat oven to 300 degrees. Grease two 9-by-5-inch loaf pans; set aside. In a mixing bowl, beat butter, sugar, and vanilla until smooth and fluffy. Add eggs one at a time, mixing just to combine after each addition; blend in milk and beat until creamy. Stir together flour, cinnamon, baking powder, and salt; beat into butter mixture until combined. Stir in marinated pecans and remaining 1/4 cup of liqueur. Pour mixture into prepared loaf pans. Bake for 1 hour and 10 minutes, or until a tester inserted in the center comes out clean. Cool in pans for 5 minutes and turn out to wire racks to cool completely. For Icing: Melt the 1/3 cup butter in a medium saucepan; remove from heat. Stir in confectioner's sugar to blend. Stir in 4 Tablespoons Praline liqueur, or more if needed to make a drizzling consistency. Drizzle each loaf with icing, and garnish with whole pecan halves. Makes 2 loaves.