Step 2 – For the filling: Heat 3 tablespoons of butter on high heat in a pan and sauté the apples for 10 minutes. Reduce heat and cook on low until golden brown. Remove from heat and add the sugar, nutmeg, cinnamon, kirsch or brandy. Stir to combine, then set aside.
Step 3 – For the dough: Beat the rest of the butter with the icing sugar in a large bowl until a pale mixture forms. Add the eggs one by one and mix well. Add the sifted flour and baking powder. Mix until a dough is formed. Do not knead.
Step 4 – Transfer the dough into a 23 cm diameter tart mold, pressing the dough into the bottom and sides of the mold. Even out the edges and pour the reserved apple filling into the mold along with the blueberries and maqui berries. Bake for 25-30 minutes or until the edges of the dough are golden brown. Serve hot or cold.