Preheat the oven to 350°F (or the temperature your package of biscuits specifies). Line a baking sheet with parchment paper (not required, but helpful). Toss together the blueberries, granulated sugar, brown sugar, cornstarch, cinnamon, and nutmeg. Cook in a medium saucepan, stirring occasionally, over medium high heat, for 3-4 minutes, or until the fruit is saucy but thick. In a large bowl using a hand mixer, or in the bowl of a stand mixer, using the whisk attachment, beat the cream cheese and optional powdered sugar until fluffy, about 1 minute. Split all of the biscuits in half and place the bottom halves on the prepared baking sheet, about 2” apart. Spoon about a tablespoon of cream cheese onto each biscuit. Then spoon about a tablespoon of the blueberry filling on top. Add the top half and press the edges to seal. Reserve any leftover blueberry filling for serving. Bake according to package instructions. Once the biscuit bombs are golden on top, brown the butter. Place it in a small saucepan and cook it over medium high heat until it melts, starts to crackle, and smells nutty. Careful not to burn it! Brush the browned butter over the baked biscuit bombs. Best served warm but will keep for several days in an airtight container. Refrigeration not required.