Melt butter in a medium saucepan over medium heat.
Add garlic, and saut 1 minute or until tender and lightly browned.
Add milk and next 3 ingredients, stirring with a whisk. Bring to a simmer, and add potatoes. Cook 2 minutes or until potatoes are smooth and fluffy, stirring occasionally. Stir in spinach; let stand 1 minute or until spinach begins to wilt.