Heat olive oil in a saucepan; add wine and lemon juice. When olive oil starts to boil, place shrimp in the pan and cook on medium heat until shrimp curls. Remove shrimp but leave wine mixture in the pan.
In the same saucepan, add onion, minced garlic, and garlic salt. Saute until the onions are transparent.
Mix 1 tablespoon flour with 1 tablespoon water to make a paste.
Add flour paste to the saucepan. Stir and cook until sauce is thick.
Pour cream in the sauce, stir, then add the cheeses one at a time, whisking constantly after each addition. The sauce should be a medium-thick consistency and smooth. If the sauce is too thick, add a little water and whisk. Remove from heat.
Place Italian bread on a serving tray in an X.
Arrange shrimp in the middle of the bread.
Spoon sauce in the middle of the bread, covering the shrimp.
Sprinkle with sliced green onions, olives, tomatoes, and crushed red pepper on top. Sprinkle more Parmesan cheese on top if you would like.