Before starting anything, cube your butter and then place it into a bowl. Put the bowl in the freezer to ensure the butter gets as cold as possible!
Make the ganache. First, put the chocolate chips into a large mixing bowl and set aside. Next, pour the heavy cream into a sauce pan and heat over medium high heat. Bring the cream to a simmer (lightly bubbling around the edges) and then remove it from the heat and pour it into the bowl with the chocolate chips. Whisk together until smooth and until the chocolate is fully incorporated into the heavy cream. Cover the ganache with tin foil or plastic wrap, then place it in the freezer to firm up.Note: you do not want to boil the heavy cream as it will be too hot to properly mix with the chocolate. In a mixing bowl, combine the dry ingredients for the chocolate cookies and whisk until fully incorporated. Set aside.
In the bowl of a standing mixer, combine the light brown sugar and white sugar. Then, add the frozen cubed butter into the bowl. With the paddle attachment, mix on low speed until the butter is fully incorporated into the sugar. If the butter/sugar mixture is sticking to the paddle or bowl, use a rubber spatula to free it from the edges of the bowl and continue mixing until combined. The end result should feel and look like cold, wet sand. This will take a few minutes since the butter is so cold! That is A okay and it's what we want.
Add the 2 large eggs into the bowl with the butter/sugar mixture and mix with the paddle attachment on medium speed until the eggs become fully incorporated into the butter/sugar mixture.
Pour half of the dry ingredients into the standing mixer bowl and mix with the paddle attachment on low speed until fully combined with the butter/sugar/egg mixture. Add the second half of the dry ingredients and continue mixing until a dough is formed.
Remove the dough from the bowl and place it onto a clean work surface. Divide it into 12 equal sized chunks and roll them into balls. Set aside. Pour about 1/2 cup of sprinkles onto a flat clean work space or plate and set next to the dough.
Remove the ganache from the freezer. One by one, flatten each ball of dough with your hand and then scoop 1 tbsp of ganache into the center of the dough, leaving about a 3/4-inch radius around the ganache so you can close it inside of the dough without it leaking. Pour about 1-2 tsp of sprinkles on top of the ganache. Take the edges of the dough and fold them together around the ganache/sprinkle filling so that the ganache is folded into the center of the dough ball. Make sure there are no openings and that the ganache is tucked in and cozy in the dough. Roll the dough ball in the sprinkles and then set aside. Repeat these steps with each piece of dough, until all the dough is filled with ganache and coated in sprinkles! Woohoo!
Place a piece of parchment paper onto a sheetpan. Put all of the balls of dough onto the parchment paper and place the sheet pan into the freezer for at least 20 minutes before baking. If freezing longer, cover the dough with cling wrap or tin foil so that it doesn't get that freezer burn taste.
Preheat the oven to 400 degrees.
Remove the dough balls from the freezer and make sure they are not stuck to the sheet pan before baking. Then, bake for 12 minutes. Allow them to cool for 10 minutes before eating! Enjoy!