Spiralized Skillet Scalloped Potatoes with Mushrooms & Onions - Sprinkles & Sea Salt

Ingredients

• 4 tbs butter
• 1 cup white onion, chopped thin
• 1 cup baby bella mushrooms, sliced
• 3 tbs flour
• 2 cups whole milk
• 6 red potatoes, spiralized
• 2 cups Gruyère cheese
• 1/2 cup grated parmesan cheese
• sea salt and pepper