Into a medium-size saucepan over medium heat, add vegan butter. When butter is melted, add the garlic. Saute for 1 minute.
Whisk in the flour until fully incorporated.
Continue whisking while slowly pouring in the milk, until no lumps remain. Cook 2-3 minutes until sauce is slightly thickened and heated through.
Add the spinach, sea salt, and ground black pepper. Stir the spinach into the sauce and continue cooking 2-3 minutes, until spinach is wilted.
Turn off the heat and remove the pot from the heat source.
Stir in the shredded parmesan cheese.