Heat the butter in a frying pan, and add cake flour. Stir well to make sure it doesn't burn. Pour in all the milk, and add the soup stock granules, salt, and pepper.
Keep stirring with a wooden spatula, being careful not to flip the the frying pan. It's done once it turns creamy.
Thinly slice the onion and rub with a teaspoon of salt. After leaving for 15 minutes, wash off the salt with running water and wring out the liquid with a paper towel.
Dock your pizza crust with a fork. I used the recipe "Basic pizza crust".
Once cooled, spread plenty of white sauce on the dough. Sprinkle some white wine (or sake) on the seafood mix, and microwave it!
Sprinkle some onions, bell peppers, mushrooms, seafood mix, and tuna on top.
Top with plenty of cheese, and bake for 10 to 12 minutes at 300.
The cheese blends well with white sauce and will melt in your mouth! The crust is crispy too, you'll certainly want to eat this homemade pizza while piping hot!