Preheat oven to 350 degrees.
Heat 1 tablespoon of olive oil in a skillet. Lightly brown the garlic, remove from heat and toss with the spinach. Place on top of the bread cubes.
Return skillet to the heat, add 2 tablespoons olive oil. Sear the portobello slices on both sides and arrange in a circle overlapping on the top of the spinach. Add more olive oil as needed. Sprinkle the cheese on top.
Beat eggs and add the half and half, cream, salt and pepper. Pour over top. Bake for 30 minutes