Grease your mini-muffin tin with the 1 Tbsp of salted butter.
If using a mini-muffin tin, cut out ten small circles or parchment paper, and place the parchment paper circles in the bottom of your greased muffin tin holes.
*If using a regular-sized muffin tin, try to make 4-5 circles of parchment paper to line the larger-sized muffin tin holes.
Preheat the oven to 375F.
Add 1 Tbsp of salted butter to a hot saute pan on the stove.
Add the half of a cup of cleaned and diced button mushrooms, along with the diced onions.
Cook for 7 minutes, stirring every minute or so.
Remove the sauteed vegetables from the stove, and add them to a mixing bowl.
Add the very finely-minced clove of black garlic, along with the whisked eggs, red pepper flakes, heavy cream, diced American cheese, and a sprinkle of Kosher salt and freshly-ground black pepper.
Mix the ingredients together.
Divide the mixture carefully among the prepared muffin holes in your muffin tin.
Bake at 375F for about 12-15 minutes, or until the eggs are cooked through but still slightly wobbly in the center.
*If using a larger muffin tin, you will need to cook these for closer to 15-17 minutes.
Remove the muffin tin from the oven, and allow them to cool at room temperature for roughly 7-10 minutes.
Carefully use a sharp small knife to separate the edges of the egg & mushroom breakfast bites from the holes in the muffin tin.
Remove the bites from the muffin tin, and garnish with the finely-sliced scallions.
Serve immediately, with a small scoop of crème fraiche on each bite.