Preheat the oven to 350 degrees and spray your mini donut pan with nonstick cooking spray.
In a large bowl, whisk together the flour, baking soda, baking powder, salt, nutmeg, and cinnamon.
In a separate bowl, whisk together the ¼ cup milk, yogurt, egg, vanilla, and brown sugar. Add in the butter and whisk until combined.
Add in the dry mixture, along with a bit of neon green dye, and whisk until combined. Add a bit more neon gel dye until desired color is reached.
Place the mixture in a frosting bag or big baggie and snip the corner of the bag off using scissors.
Pipe the mixture into each donut cavity until ⅔ full. Tap on the counter aggressively to flatten out the batter. It’s thick, so it needs a harder tap to spread.
Bake for 7 minutes or until very lightly golden brown on the outside and fluffed up.
Remove from the oven and let cool in the pan for about 10 minutes before moving to a cooling rack to finish cooling all the way through.
While the donuts are cooling, combine the powdered sugar and remaining milk. Mix until an icing has formed. Add some neon green dye and mix. Only mix in a little bit at a time and keep adding until the desired mixture has been reached.
Add your dusting sugar to a bowl. Dip the top of each donut into the icing, tapping it on the side of the bowl to ensure excess frosting falls away.
Dip the top of each donut into the dusting sugar and place one heart sprinkle in the upper-right corner of each donut.
Let sit and dry for a few minutes and enjoy!