In a Dutch oven, melt butter over medium-high heat and add diced yellow onion. Cook until onions are translucent.

Add in garlic paste or minced garlic and cook until fragrant.

Add in flour and stir to create a roux.

Gradually add half and half or whole milk, stirring constantly to avoid lumps.

Once the sauce begins to thicken, add in lemon juice and zest, red pepper flakes, chicken base (if using), salt, pepper, garlic powder, onion powder, and cajun seasoning (to taste).

Stir in cream cheese until melted and fully incorporated.

Add in shredded parmesan and mozzarella cheeses, stirring until melted.

Carefully fold in the shrimp, crab meat, and chopped spinach.

Cook on low heat until seafood is fully cooked and spinach is wilted.

Serve hot with baguette or tortilla chips for dipping.