Slice potatoes and place into a bowl of ice water until ready to assemble. Preheat oven to 400 degrees.
In a pan, melt butter over medium heat. Once melted, add garlic and cook until fragrant. About 4 minutes.
Add flour and cook to remove raw flour taste, about 3 minutes.
Carefully and slowly, add about 1/3 of the milk to the pan while whisking to remove lumps. Slowly stream in remaining milk while whisking to ensure no clumps appear.
Add worcestershire sauce, spices and whisk until combined. Continue to stir until sauce just coats the back of a spoon. Add parmesan and immediately remove from heat. Bechamel sauce should still be quite thin.
If making ahead. Allow sauce to cool and put in airtight container. To assemble, move forward to next step.
To assemble, spray baking dish with cooking spray. Assemble a layer of sliced potatoes, slightly overlapping. Top with a spoonful of sauce per row and use back of spoon to spread. You do not need much sauce between layers as sauce will spread as it bakes. Top with a bit of the cheese, about 1/3 of the mixture and repeat, building 2 more layers with the potatoes, sauce and cheese.
Cover with foil and bake at 400 degrees for 35 minutes. Remove from foil and bake an additional 25-30 minutes, or until potatoes are bubbling in the center.
Remove and allow to rest for at least 5 minutes before serving. Enjoy