Preheat oven to 350 degrees. Wash the potatoes. Prick a few holes with a fork in the potato, wrap in aluminum foil, & place on a baking sheet. Bake for 1 hour. Remove from the oven and let cool on a wire rack until cool enough to handle. Remove the tin foil.
Preheat the oven to 450 degrees.
Combine the garlic & oil in a bowl & microwave for 30 seconds with a paper towel on top. Set aside.
Cut the potatoes in half, lengthwise - and scoop out the insides, leaving a thin rim around the outside for structure/support. Remove the minced garlic from the oil with a slotted spoon, and reserve. Brush the garlic infused oil onto the insides of the potatoes. Bake for 12 minutes.
In a skillet, saute the sausage & onion until nicely browned. Stir in the reserved minced garlic (from the oil) and cook 1-2 additional minutes. Turn off the heat. Mix in half of the cheese & the sun dried tomatoes.
Divide the mixture evenly between the potato skins. Sprinkle on the remaining cheese & bake in the oven for 5 minutes.
Sprinkle with basil leaves & serve with sour cream and marinara sauce.