Slice potatoes into thin rounds and place in a bowlIn a pan, melt butter over medium heatAdd garlic and onion and sautee for about 5 minutesAdd flour and stir togetherAdd vegetable broth, milk, salt, pepper, rosemary, and thymeStir the mixture on medium high heat until it starts to thicken slightly (around 5-7 minutes)Add the ¾ cup of grated parmesan and stir until meltedGrease a 13 X 9 dish with olive oil or cooking sprayPlace ½ of the potatoes in the dish (they should evenly cover the bottom of the dish)Cover potatoes with ½ of the sauce mixturePlace ¾ cup of white cheddar cheese on topCover with remaining potatoes (another even layer)Top with remaining sauce and remaining ¾ cup of cheddar cheese on topCover with foil and bake at 375 for 35 minutesRemove foil and bake for another 15-25 minutes, or until potatoes are cooked through and the top starts to brown(optional) Crank up heat to 425 for the last few minutes for extra crispinessTop with fresh parsley