
Cook mushrooms and garlic in olive oil over medium heat until tender. Set aside to cool.
Whisk the egg mixture in a large bowl. Season with salt & pepper. Add bread and toss to combine. Let sit 5 minutes and toss again until the liquid is absorbed. Stir in mushrooms, brie and ½ of the Havarti cheese.
Add the mixture to a greased 2 qt baking dish (or 9x9 pan). Cover and refrigerate at least 30 minutes or up to 24 hours.
Preheat oven to 350°F.
Bake covered for 30 minutes. Uncover, top with remaining cheese and bake an additional 15-20 minutes or until set in the middle.
Rest 10 minutes before cutting.