– ½ cup unsalted butter – 1 cup unsweetened applesauce – ¼ cup peeled and grated apple – ½ cup granulated sugar – ½ cup light brown sugar – 2 cups all-purpose flour – 1 ½ tsp. ground cinnamon – 1 tsp. baking powder – ½ tsp. baking soda – ¼ tsp. ground nutmeg – 1 large egg for the streusel topping: – 2 Tbsp. all-purpose flour – 2 Tbsp. brown sugar – ⅛ tsp. ground cinnamon – pinch of fine sea salt – 2 Tbsp. unsalted butter, melted