Preheat oven and follow directions on pizza dough. (Most will have you cook the dough for about 5 minutes before adding the toppings). Add white sauce, mozz, cream cheese, and jalapenos (in that order) and finish baking time according to dough package. Remove, cool, and serve.
For the white sauce: In a small saucepan over medium heat, melt butter and add garlic powder. Add flour and stir until the butter and flour are well combined. Pour in milk, stirring constantly as it thickens. Add more milk depending on desired consistency. (Use as much of this as you like on your pizza, I usually have some left over).