Add all the butter to the Instant Pot and melt. Once melted add the flour and cook for a minute. Once the butter and flour have come together add in 1/3 of the milk from the 2 1/4 measured glass. This will help with not getting lumps. They will mix together very quickly as this happens add the remaining milk from the same measured glass, holding back the additional 1 cup of milk.
Stir, stir, stir...The sauce will come together, but not too thick and will coat the back of a spoon. This only takes a few minutes. About 2 to 3. Stir, Stir Stir. Then its time to add in the cheese. Start with a cup of cheese and combine. Everything will start to get tight fast. Add in either, the remaining cheese, or add in some of the milk. You have all the control here to achieve the consistency you want. Add in a pinch of white or black pepper. No salt needed. The cheese brings the salt needed.
Check the oven and pull out the Texas toast. Ladle the Cheesy Mornay sauce over the top of the Turkey or Chicken. mmm...Then add 4 pieces of bacon to the top. I like placing two going in one direction and the other two a different direction for a nice presentation. Add a sprinkle of papkira and your all set.