Start by peeling and dicing your apples into small, even pieces. I like to toss them lightly in cinnamon so every bite has flavor. This step ensures the apples stay tender but not mushy when baked.
In a large bowl, combine melted butter, brown sugar, eggs, and vanilla. I usually whisk for a minute to make sure it’s smooth and glossy. This mixture forms the rich base for the blondies.
In a separate bowl, whisk together flour, baking powder, salt, and cinnamon. Mixing dry ingredients separately helps prevent clumps and ensures even distribution.
Gently fold the dry ingredients into the wet mixture until just combined. Be careful not to overmix; I always stop when I see no flour streaks. Overmixing can make the blondies dense.
Fold in the diced apples and half of the caramel sauce. Pour the batter into a greased 9x13-inch pan. I like to drizzle the remaining caramel on top for a beautiful marbled effect.
Bake at 350°F (175°C) for about 35 minutes, or until a toothpick comes out mostly clean with a few moist crumbs. I usually start checking at 30 minutes to make sure they don’t overbake.
Let the blondies cool in the pan for at least 15 minutes. I find chilling them slightly makes them easier to cut and enhances the caramel flavor.