In a large saucepan, stir together the cream, Shiner Bock, granulated sugar, brown sugar, and salt. Place over medium-low heat and cook just until the mixture is warm—do not let it boil—about 3-5 minutes.
When the cream is warm, scoop out 1/4 cup of the mixture and stir into the beaten egg yolks until well combined. Slowly pour the cream and egg yolks back into the pot and while stirring, continue to cook until the mixture is thickened and coats the back of a spoon, about 2 to 4 minutes. Again, do not let it boil. Remove the cream mixture from heat, stir in the vanilla, and then cool covered in the refrigerator for at least 4 hours.
After the cream has cooled, freeze in your ice-cream machine according to the manufacturer’s instructions. Chill in the freezer for 4 hours for a firmer ice cream or serve immediately for a softer ice cream.
If you like, serve topped with warmed cajeta and crushed peanuts.
If you don’t have Shiner Bock available to you, you could substitute another brand of bock beer. A stout or even root beer could work well, too.