Cut potatoes into bite sized pieces coat with olive oil. Roast in 425 degree oven for 20-30 minutes or until done. While the potatoes roast, melt 2 tablespoons butter in a small skillet over medium heat. When the butter starts to sizzle, add 1 teaspoon ground cumin, 1 teaspoon chili powder, 1 teaspoon dry mustard, 1/8 teaspoon cayenne pepper, 1 medium garlic clove, minced, and cook 1 fragrant, 30 seconds to 1 minute. Transfer roasted potatoes to a serving bowl. Pour spiced butter over the potatoes, toss, and serve immediately.