Frango na púcara - portuguese style crock pot chicken

Ingredients

• 1 large chicken
• 4 large onions
• 2 garlic cloves
• 1 shot glass of Porto Wine
• 1 shot glass of água ardente
• 1 glass of white wine
• 2 tablespoons of butter or butter flavored margarine
• 1 large tablespoon of prepared mustard
• Kosher salt
• Black pepper