Preheat oven to 350°F. Grease a 8x8 or 9x9 pan, then line with parchment. In a large bowl, cream together sweetener and warm butter with a hand mixer until light and fluffy, about 5 minutes. Add in cream cheese and vanilla extract, and continue mixing together until there are no lumps of cream cheese, about another 3-5 minutes.Add in eggs one at a time until completely incorporated, but don't over mix.
In a separate bowl, whisk together almond flour, coconut flour, salt, baking soda, and xanthan gum.Combine the wet and the dry ingredients, folding together the batter with a rubber spatula. Don't over mix.
Fold in the chocolate chips, reserving some for the top. Spread the batter into the prepared baking pan and smooth the top to even it out. Press in the remaining chocolate chips all over the top. Bake for 25-30 minutes, until a toothpick comes out mostly clean, and the edges are lightly browned.
Sprinkle with flakey sea salt, and allow to cool in the pan for 10 minutes, before transferring to a wire cooling rack for at least 1 hour before cutting and serving. Cut in, and enjoy!
This makes 12 large size bars, or 16 medium sized bars. These will store in the fridge in an air tight container for up to 1 week, or in the freezer for 3 months if wrapped tightly in plastic and store in an air-tight container.