Preheat your oven to 375°F and grease all of the wells of a standard size muffin pan with nonstick spray. Whisk together one egg with one tablespoon of water to use as an egg wash and set aside.
Using a standard rolling pin, or a double sided rolling pan if you have mobility issues, roll, your crescent dough out on a lightly floured piece of parchment paper to about 12 inches by 8 inches.
If you have the time and space, place the parchment paper with the dough on a sheet pan into the freezer while you make your almond cream.
Using a hand mixer, or by hand, cream together the butter and sugar until light and fluffy, about 2 to 3 minutes. Mix in the almond flour until fully blended. Add in the egg and the almond extract, mixing until it’s all combined and fluffy.
Remove your crescent dough from the freezer and place the parchment paper and dough on your work surface Using an offset spatula, or silicone spatula, spread the frangipane evenly over the surface of the dough.
Using a knife or a pizza cutter, slice into 12 strips along the 8 inch side (so shorter strips).
Tip: To make this easier, slice your dough in half. Then slice each of those pieces in half. You now have 4 pieces. Slice each of those 4 pieces into 3 strips. You now have 12 almond cream covered strips.
Roll each strip up and place into one of the greased wells until all the strips are in the pan. Brush the top of each almond croissant muffin with a little bit of the egg wash and then top with a few sliced almonds.
Bake at 375°F for 20 to 25 minutes, or until golden brown. Let cool for 5 minutes in the pan and then transfer them to a wire rack to cool for a bit. Dust with powdered sugar and enjoy!