Scalloped Potatoes - Good Food St. Louis

Ingredients

• 4 large Russet or Yukon Gold potatoes (sliced thinly)
• 1/4 cup butter
• 1/2 onion (diced)
• 1 clove garlic
• 1/4 cup all-purpose flour
• 2 cups half and half cream
• 1/2 tsp. Kosher salt
• 1/2 tsp. ground black
• 1/8 tsp. cayenne pepper
• 1 cup grated Gruyere cheese
• 1 cup grated Cheddar cheese