In a large bowl, whisk together butter, sweetener, cocoa powder, eggs, vanilla extract, and salt. Stir in almond flour until just combined; do not overmix.
Using a silicone mini muffin pan, divide the brownie mixture between 16 wells. Place the silicone pan on top of a sturdier baking sheet, then place both in the oven on the center rack.
Bake for 14 to 18 minutes, depending on how you prefer the texture and doneness of your brownies. Use the toothpick test to determine doneness and adjust the baking time accordingly. Stick a toothpick in the center of the brownie and if it is covered in wet better when removed, bake longer. For fudge-like brownies, the toothpick will have crumbs attached once removed. For cake-like brownies, the toothpick will be completely clean once removed.
Nutrition info is for one keto brownie bite and without optional toppings; each brownie has 1g net carbs.