Add 2 tablespoons vegetable oil to a skillet and saute onions until they are translucent and browned.
For the Sauce
To another saucepan, melt butter* on medium heat. Add flour and cook 2 minutes, stirring constantly. Add milk, salt and pepper, and whisk. Bring to a boil, whisking constantly. Reduce heat immediately after it reaches the boiling point then simmer until ready to ladle on sliders.
Assemble the Sandwich
Layer turkey, bacon and cheese on the bottom half of bun. Add caramelized onions to the top half of bun. Broil in oven until cheese melts. Remove from oven. Ladle white sauce over cheese and place top bun on the slider.
Serve immediately. Enjoy!
Turkey amount and quantity really depends on personal preference. *You can use bacon grease instead of butter as the fat for your cream sauce, if you prefer. If you do this, omit the 2 tablespoon butter and continue with sauce as directed.