Melt the butter over medium heat in a medium sized skillet.
1 tablespoon unsalted butter
Add in the garlic and sauté until just soft. Then whisk in the flour.
3 garlic cloves, 1/2 tablespoon all purpose flour
Turn the heat to low and very slowly (starting with just a tablespoon or two at a time), whisk in the whole milk and then the heavy cream.
3/4 cup whole milk, 1/4 cup heavy cream
Bring to a simmer and add the chopped spinach a little at a time, stirring, until all of it is wilted.
3 cups baby spinach
Stir in 1/4 cup freshly grated parmesan cheese. Continue stirring until it melts. Season with salt and pepper to taste.
1/4 cup parmesan cheese, salt and pepper