Lemon Blueberry Layer Cake

Ingredients

• 1 cup (230g) unsalted butter, softened to room temperature
• 1 and 1/4 cups ((250g) granulated sugar)
• 1/2 cup (100g) packed light brown sugar
• 4 large eggs (, at room temperature)
• 1 Tablespoon vanilla extract
• 3 cups (360g) sifted all-purpose flour, careful not to overmeasure
• 1 Tablespoon baking powder
• 1/2 teaspoon salt
• 1 cup (240ml) buttermilk3
• zest + juice of 3 medium lemons4
• 1 and 1/2 cups blueberries (, fresh (258g) or non-thawed frozen (275g))
• 1 Tablespoon all-purpose flour
• 8 ounces (224g) full-fat cream cheese, softened to room temperature
• 1/2 cup (115g) unsalted butter, softened to room temperature
• 3 and 1/2 cups ((420g) confectioners' sugar)
• 1 – 2 Tablespoons (15-30ml) heavy cream
• 1 teaspoon vanilla extract
• pinch salt