Caramelized Onion Spinach and Artichoke Dip | Erin’s Recipes | Umami

Ingredients

• 2 tablespoons olive oil
• 2 medium Spanish yellow onions, thinly sliced
• 2 teaspoons diamond crystal kosher salt (use 1 tsp for Mortons)
• 6-8 cloves minced garlic
• 8 oz cream cheese
• 1 cup sour cream
• 4 tablespoons mayonnaise (preferably Japanese)
• 1 cup freshly grated gruyere cheese
• 1 cup freshly grated low-moisture mozzarella (sometimes labeled as 'part skim')
• 16 oz frozen spinach, thawed (I use microwave), water pressed out (use a sieve), and chopped
• 14 oz (1 can) artichoke hearts, drained and chopped
• Freshly grated black pepper, to taste
• Red pepper flakes, to taste