Heat olive oil and smashed garlic in a small saucepan over medium heat until garlic bubbles steadily for 3-4 minutes.

Add fresh rosemary sprigs to the oil, remove from heat, and let cool to room temperature. This Rosemary-Garlic Oil can be made up to 5 days in advance and stored, covered, in the refrigerator.

Toss chicken thighs in a medium bowl with 2 tablespoons of Rosemary-Garlic Oil, 1 teaspoon fresh rosemary, 1 teaspoon kosher salt, and 1/2 teaspoon freshly ground black pepper. Marinate for at least a couple of hours or up to one day ahead.

Divide 1/2 cup of Rosemary-Garlic Oil into 2 small bowls (one for grilling, one for serving).

Thread three pieces of sausage, three pieces of chicken, and four sage leaves alternately onto six 12" metal or soaked wooden skewers.

Grill the skewers, covered, until one side is browned and has good grill marks, about 4 minutes.

Brush with some of the rosemary-garlic oil, flip and cook the other side until it, too, has good grill marks, about 4 minutes.

Brush with more oil and flip again.

Continue cooking, flipping, and brushing with oil until the sausage and chicken are both cooked through but not overdone, about another 10 minutes.

Let cool for a couple of minutes and then arrange on a platter, drizzle on the remaining oil, and set out for guests to serve themselves.