Blueberry lemon jam: add blueberries, sugar, and lemon juice to a small saucepan over medium heat. Stir everything together and cook for about 20 to 25 minutes, stirring often, until the jam has thickened.

Remove the jam to a sealed container or jar and store in the fridge until time to use. 

Blueberry lemon mascarpone: in a small bowl, combine mascarpone, blueberry lemon jam, and lemon zest. Stir until combined fully.

Serve on toast or a bagel. Store in the fridge for up to a month. 

Sandwich broiling: slice the roll if needed. Spread a thin layer of blueberry lemon mascarpone on the bottom slice. Top that with slices of turkey and bacon. Cover the bacon with the shredded cheese and place both the top and bottom of the roll, cut side up, under a broiler and broil until the cheese has melted and the top roll is a little bit toasty.

Remove both sandwich halves from the broiler and spread a thin layer of blueberry lemon mascarpone on the toasted top half. Sprinkle on a small handful of crispy fried onions onto the melted cheese and then close the sandwich.

Panini: butter both sides of the sandwich and cook it in a panini press until the bread gets crusty and browned. If you do not have a panini press, you can use a hot cast-iron skillet with another skillet on top of the sandwich, pressing it down. This will grill the bottom side, and you will have to flip the sandwich, but it will work just fine.

Once both sides of the bread are browned and the cheese is melty, serve and enjoy.