Melt butter in a medium skillet over medium heat.

Add thinly sliced apples, cinnamon, and brown sugar to the skillet.

Toss until apples are coated and sugar is melted, about 2-4 minutes. Remove from heat and set aside.

Preheat oven to 425°F (220°C). Line baking sheet with parchment paper.

In a large bowl, whisk together flour, sugar, baking powder, and salt.

Add chilled butter cubes and cut in until a coarse meal forms.

In a small bowl, whisk together heavy cream, egg, and mix into the dry ingredients.

Gradually add buttermilk and toss until moist clumps form.

Gather dough into a ball and flatten into a disk.

Generously dust a clean work surface with all-purpose flour.

Spoon the dough onto the floured surface and pat it into a small rectangle.

Use a rolling pin to gently roll the dough into a 1/2-inch thick rectangle, about 7x10 inches.

Arrange cooled apples in a single layer over half of the rolled out biscuit dough.

Fold the bare side of the dough over the apples and gently press the edges to seal.

Pat the dough into a 6x8 inch rectangle.

Use a sharp knife to slice the dough into 12 squares.

Use a spatula to place each biscuit onto the prepared baking sheet, about 2 inches apart.

In a small bowl, whisk together raw sugar (or granulated), cinnamon, and salt for the topping.

Brush each biscuit top with beaten egg and sprinkle generously with the cinnamon sugar mixture.

Bake for 12-14 minutes until the biscuits are risen and golden brown.

Remove from the oven and serve warm, or cool completely before storing in an airtight container.

Biscuits are best enjoyed within two days of baking.