Preheat the oven to 375 degrees F (190 degrees C). Grease a pie plate and dust with bread crumbs
Combine melted butter, 1/2 cup sugar, and vanilla bean seeds in a bowl. Add eggs and stir to combine. Mix flour, baking powder, and salt in a bowl and add to butter mixture. Add milk if batter is too thick
Pour batter into the prepared pie plate. Distribute apple slices in a thick layer on top of the batter. Dot with cubed butter and sprinkle with 1/4 cup sugar.
Bake in the preheated oven until a toothpick inserted into the center comes out clean, 30 to 45 minutes. Cool on a wire rack for 5 minutes. Run a table knife around the edges to loosen. Invert carefully onto a serving plate or cooling rack. Let cool completely
