Preheat oven to 350 degrees F. Spray a 12-cup muffin tin with cooking spray. Line a sheet tray with parchment paper.
In a medium bowl, whisk together flour, baking powder and salt. Stir in heavy cream until a sticky dough forms.
Turn out onto a lightly floured surface and knead gently until the dough is smooth. With a rolling pin, roll dough into a rectangle, about ½” thick. With a pizza cutter, slice the rectangle into 1” pieces (you should have about 60 pieces).
In a small saucepan over low heat, add the butter and brown sugar, whisking until the butter melts. Bring to a boil and cook for an additional minute. Remove from heat.
In a shallow bowl, whisk together the sugar and the cinnamon. Toss the dough pieces, 10 at a time in the sugar mixture. Add about 5 pieces of dough to each muffin cup shoving a few more pieces of apple in between the dough pieces. Once all muffin cups have been filled with dough and apples, pour the remaining sugar sauce on top of each muffin.
Place the muffin tin on top of the sheet tray (sugar will spill over) and bake for about 15 minute or until biscuit pieces have risen and the muffins are cooked all the way through.
Remove from the oven and let sit for about 5 minutes. Turn muffins out on the parchment lined sheet tray.
While the muffins are cooling, whisk together the powdered sugar, milk and vanilla.
Drizzle icing on top of muffins, place on a serving platter and enjoy!