Blueberry Layered Cake - Blueberries

Ingredients

• 1 box butter cake mix (you can also use yellow or white cake)
• Ingredients for cake mix (eggs, butter or oil, water)
• 2 cups frozen blueberries, rinsed and patted dry
• 2 tablespoons maple syrup
• Juice from half of a lemon
• 1 cup unsalted butter (2 sticks, at room temperature)
• 4 cups powdered sugar, sifted
• 3-4 tablespoons heavy cream or milk
• 1 teaspoon vanilla extract