Preheat oven to 300 degrees. Spray a muffin pan with nonstick spray.
Remove the rind from the brie and discard. Roughly chop 2/3 of the brie to be used in the egg mixture. Dice the remaining brie and set aside (we'll use it to add into each muffin cup so every bite has melty, cheesy pockets).
In a small skillet over medium-low heat, add the truffle oil and butter. Sauté the diced mushrooms about 5–7 minutes or until tender. Add the minced garlic and cook for 30 seconds more, just until fragrant. Season with salt and pepper and set aside to cool while preparing the egg batter.
Using a food processor (recommended) or a blender, blend the cottage cheese for about 1 minutes or until it's whipped smooth with no curds. Into the same food processor, add in the eggs, brie, 1 cup monterey jack cheese, cornstarch, hot sauce, and 1/4 tsp salt and 1/2 tsp pepper. Blend until combined and smooth.
Get a pot or kettle of water boiled on the stove and pour it into a casserole dish placed on the bottom rack in the oven, enough water to come halfway up the pan. Close the oven immediately to capture the steam inside.
Pour the egg mixture into a bowl and add in the mushrooms, whisking to combine. Divide the egg mixture evenly among each cavity in the muffin pan, filling them almost to the top. Add a generous pinch of each remaining cheese to each muffin, using a spoon to push the cheeses to the center.
Place the pan into the oven on the center rack (with the steam tray remaining in the oven on the rack below). Bake for 25 minutes or until the eggs are set and no longer jiggly.