Peel the potatoes and slice thinly. Place sliced potatoes in a large pot and cover with water. Soak while you’re preparing the rest of the recipe.

Add the coconut milk and chopped onion and garlic to a large skillet and bring to a full boil. Cook, stirring occasionally until the onion and garlic are very fragrant, about 5 minutes. Whisk in the gluten-free all-purpose flour and sea salt and continue cooking until thick, about 3 minutes. Set aside until ready to use.

Chop the sun-dried tomatoes, olives, and peppers.

Preheat the oven to 375 degrees F and lightly spray or oil a large 13" x 9" casserole dish.

Drain the sliced potatoes. Add ⅓ of the slices to the bottom of the casserole dish (it’s okay if the slices overlap!). Add ⅓ of the sauce and spread over the potato slices. Sprinkle ⅓ of the sun-dried tomatoes, olives, and peppers, followed by ⅓ of the cheese.

Repeat for the remaining ingredients, creating a total of three layers. Note: I save a little more than ⅓ of the sauce and cheese for the top layer to be sure the slices are well-covered in sauce and cheese.

Cover the casserole dish with foil and bake on the center rack of the oven for 50 to 60 minutes, or until the potatoes are cooked through. Remove the foil, and increase the oven heat to 450. Bake 10 to 15 minutes longer, until the cheese has turned golden-brown.

Allow scalloped potatoes to cool at least 10 minutes before serving.