Creating White Sauce Sausage Pizza can be simplified by following these simple steps:

1. Preheat the Oven: Preheat your oven to 425°F (220°C).
2. Make the White Sauce: In a saucepan, melt the butter over medium heat. Add flour and whisk until combined.
3. Add Milk: Gradually pour in the milk, whisking constantly until the mixture thickens.
4. Season the Sauce: Stir in garlic powder, salt, pepper, and Parmesan cheese. Remove from heat and set aside.
5. Prepare the Pizza Crust: If using a pre-made crust, place it on a pizza stone or baking sheet.
6. Spread the Sauce: Evenly spread the white sauce over the pizza crust.
7. Add Cheese: Sprinkle shredded mozzarella cheese over the sauce.
8. Add Sausage: Distribute the crumbled sausage evenly across the pizza.
9. Add Optional Toppings: If desired, add sliced mushrooms or any other toppings you prefer.
10. Bake the Pizza: Place the pizza in the preheated oven and bake for 25-30 minutes, or until the crust is golden and the cheese is bubbly.
11. Cool: Remove the pizza from the oven and let it cool for 10-15 minutes.
12. Garnish: Optionally, garnish with fresh basil leaves before slicing.

These steps will guide you in creating this incredible pizza effortlessly.