Preheat oven to 350°F (177°C). Spray the donut pan (heart-shaped donut pan or regular donut pan) with non-stick spray. Set aside.

Whisk the flour, baking powder, baking soda, salt, cinnamon, and nutmeg together in a medium bowl. Set aside. Whisk the egg, brown sugar, and buttermilk together until smooth. Add the melted butter and vanilla, whisking until fully combined. Pour the wet ingredients into the dry ingredients and mix until just combined. Do not overmix. The batter will be very thick.

Spoon the batter into the donut cavities—I highly recommend using a large zipped-top bag for ease. Cut a corner off the bottom of the bag and pipe the batter into each donut cup, filling only 1/2 to 2/3 full. If baking hearts, do not fill up too much or the donuts won’t have a hole in the center (they’ll puff up too much).

Bake for 8-10 minutes or until the edges are lightly browned. Allow to cool in the pan for about two minutes then place each on a wire rack set on top of a baking sheet or parchment paper (to catch any sprinkles or glaze in step 5). Bake the remaining donut batter (there is usually enough batter for 2-3 more donuts) and once baked, transfer to the wire rack. Allow donuts to cool down until you can handle them.

In a medium bowl, whisk the glaze ingredients together until completely smooth. Add more cream to thin or more confectioners’ sugar to thicken, if desired. I always add a little salt to offset the sweetness. Dip each donut into the glaze, then place back on the rack. Top with sprinkles. Donuts are best served immediately. Leftovers keep well covered tightly in the refrigerator for up to 3 days. If glazed lightly, the glaze will somewhat set after a few hours.