Melt 3 tablespoons of butter in a skillet over medium-low heat. Add the sliced onions and cook, stirring occasionally, for 20 minutes until they turn deep golden brown. Remove from heat and let cool slightly.
Preheat the oven to 375 degrees and lightly grease a loaf pan.
In a large bowl, combine the ground beef, 6 ounces of the shredded smoked Gouda, the cooled caramelized onions, eggs, almond flour, salt, pepper, and garlic powder. Mix with your hands until evenly blended.
Transfer the mixture to the prepared loaf pan and press it into an even shape. Sprinkle the remaining 2 ounces of smoked Gouda over the top.
Bake for 50 to 55 minutes until the internal temperature reaches 160 degrees. Let the meatloaf rest for 10 minutes before slicing.