Cut a slice, about 5-inches in diameter, off top of bread; reserve slice. Remove center portion of bread, leaving a shell. Use bread pieces for bread crumbs or stuffing. In a skillet, heat 4 tablespoons of the butter, lightly sauté onions and half of the garlic. Remove from heat and add cream cheese, sour cream, and cheddar cheese; mix well. Fold in artichoke hearts. Put mixture into bread shell; cover with reserved slice of bread. Wrap in heavy foil and bake in electric oven at 350°F for 1 hour. In a small skillet, heat remaining 4 tablespoons butter; add remaining minced garlic and sauté lightly. Pour butter mixture over baguettes; wrap in foil. Bake with dip for the last 10 to 15 minutes. Dip bread slices into artichoke dip. Remaining bread shell can be served with soup or salad. Makes about 20 servings.