Sauté garlic in hot oil in a small skillet coated with cooking spray over medium-high heat 2 to 3 minutes or until tender. Set aside.
Cook potatoes in a Dutch oven in boiling water to cover 30 minutes or until tender; drain.
Mash potatoes in a large bowl. Stir in garlic, 1/4 cup Gouda cheese, half-and-half, and next 4 ingredients until blended. Spoon mixture into a 13- x 9-inch baking dish coated with cooking spray. Sprinkle evenly with remaining 1/2 cup Gouda.
Bake at 350° for 30 minutes or until cheese melts.