Set the oven to 375°F (190°C). Grease a 9x13-inch baking dish with butter to prevent sticking and enhance flavor.

In a large skillet, heat the vegetable oil over medium-high heat. Add the diced red onion and minced garlic, sautéing until the onion softens and turns translucent, about 5 to 7 minutes. Stir in the diced bacon, red bell pepper, and minced jalapeños. Cook until the bacon becomes crisp and golden brown, approximately 7 to 10 minutes.

In a large mixing bowl, combine the beer, barbecue sauce, brown sugar, and molasses, stirring until well blended. Add the cooked pinto beans and the sautéed bacon-onion mixture. Season with garlic salt and cracked black pepper to taste. Stir everything together until evenly coated.

Pour the bean mixture into the greased baking dish, spreading it evenly. Place in the preheated oven and bake for about 45 minutes, or until the beans are bubbling and the top has developed a rich, caramelized layer.

Remove from the oven and let the baked beans rest for a few minutes before serving. Enjoy as a hearty side dish at barbecues, cookouts, or alongside your favorite grilled meats.