Melt butter in a small saucepan on medium heat. Add the grated onion and cook for 2 to 3 minutes. Add the bourbon whisky, the maple syrup, tomato paste, rosemary, salt and pepper. Whisk to combine. Bring to a low simmer.

Preheat oven to 350°F. Place chicken wings in a bowl and pour half of the bourbon maple sauce over the wings, returning the remaining sauce to the stovetop. Toss the wings with the sauce to coat. Arrange the wings on an oiled, foil-lined baking pan, with space between each wing.

Roast the wings at 350°F for 20 minutes, then turn the wings over and roast them an additional 12- 15 minutes, or until nicely browned. Lower the heat or remove from oven if the wings start getting too dark.

While the wings are roasting, simmer the remaining sauce until it thickens slightly and can coat the back of a spoon, then remove from heat.

When wings are done, remove them to a bowl and toss with the remaining sauce.