In a saucepan, add in the hot italian sausage links. Be sure you remove the sausage from its casing.
Add in the chopped onions and break the sausage apart with a spoon. Place over medium heat and let brown up and onions to become soft. Remove from heat and drain off the fat from the sausage.
Add in the ragu sauce and stir. Set aside.
In a medium bowl, add in the ricotta cheese, parmesan cheese, garlic powder, parsley, and salt. Stir to combine.
Butter one side of texas toast. Do this with all 6 pieces of bread.
Add a layer of ricotta cheese mixture, sausage and cheese and two slices of mozzarella cheese.
Place another slice of texas toast on top butter side up.
Place onto a grill pan that's been heating over medium/low heat.
Let the bread become golden brown and flip. Repeat with the second side. Make sure the pan isn't too hot that it's browning up the bread before the mozzarella cheese has a chance to melt. If this happens, reduce heat some.