Wash and trim the spinach.
Steam the spinach until wilted.
Cool in the refrigerator.
Squeeze excess liquid completely out of the steamed spinach and transfer to a large bowl.
In a large pot, bring heavy cream to a high simmer.
Transfer the hot cream to a large bowl and blend with a stick blender on low until a vortex is seen.
Add shredded gouda and blend on high until a thick cheese sauce is formed (add cheese in batches to ensure the cream stays hot).
Heat lemon juice and salt in a small pot and fold into the cheese sauce.
In a large bowl, mix all ingredients together and gently massage with your hands until all ingredients are evenly dispersed and the panko has soaked up all of the oil.
Spread the panko mix on a parchment paper-lined baking tray (no more than 1/4" high to promote toasting).
Bake in the oven until golden brown.
Let cool for 1 hour.
Mix the reserved gouda/cream puree with the cooled steamed/drained spinach.
Top with the panko and serve.