Melt the butter in a medium saucepan on top of the stove over medium high heat; then add the garlic. Stir until the flavor of the garlic starts to release; then add the flour forming a roux
Reduce heat to low; then add the milk and both cheeses. Whisk together until all of the cheese has melted and the sauce becomes thick
Finally, add the artichokes and spinach and mix until well blended. Serve hot with chips, vegetables or cubed bread