Make cracker topping: Preheat the oven to 400 F. Crush cracker crumbs in a food processor or plastic bag. Transfer to a bowl and mix with melted butter, grated cheese, garlic powder, kosher salt and cracked black pepper to taste. Transfer to a small sheet pan and bake for 5-10 minutes, or until golden brown and crunchy. Reserve for topping spinach.
Blanch spinach: Bring a large pot of water to a boil and blanch the spinach for 1 minute. Remove spinach, drain and squeeze out all excess water. Blot dry with a paper towel and roughly chop.
Saute aromatics: In a medium saute pan set over medium heat, add butter. Once melted, add in shallots and cook for 2-3 minutes, or until translucent. Stir in garlic and cook for an additional 1-2 minutes.
Make cream sauce: Whisk in the heavy whipping cream, cream cheese cubes, grated cheese, nutmeg, a few turns of cracked black pepper and a heavy pinch of kosher salt. Whisk together until smooth and melted, about 3-4 minutes.
Add spinach and thicken: Add in the spinach and stir together. Cook on medium-low for 5-10 minutes, or until the spinach has creamed together. If spinach is too thick, add in a bit more cream and taste test for salt and pepper.
Finish with topping: Transfer to a serving bowl. Top with crunchy topping before serving.