Heat 2 tablespoons of butter in a small saucepan over medium heat. Add garlic and jalapeno, and saute until soft. Pour in chicken stock, 1/4 cup tequila, and 3 tablespoons lime juice. Bring to a boil, then lower the heat and simmer until the mixture is reduced to a paste, about 30 minutes. Stir occasionally to make sure it is not sticking.