Mix olive oil, balsamic vinegar, thyme, rosemary, minced garlic, salt, and pepper together in a bowl. Set aside for flavors to blend, about 40 minutes.
Preheat an oven to 475 degrees F (245 degrees C).
Combine potatoes, pumpkin, onions, red chile pepper, and whole garlic clove in a large bowl; pour olive oil mixture over vegetables and toss to coat. Spread vegetables in a roasting pan in 1 even layer.
Roast in the preheated oven, stirring 1 or 2 times, until vegetables are tender, about 1 hour 10 minutes.