Preheat oven to 350°F.
Grease a 1½-quart or 11 x 9 baking dish.
Boil salted water, cook pasta according to package directions, then drain.
Melt butter in a large saucepan over medium heat.
Add onion and minced jalapeños; cook for 3–5 minutes until softened.
Stir in garlic; cook 1 minute.
Add flour and stir constantly for 1–2 minutes until golden.
Slowly whisk in milk; cook until thickened (about 3 minutes). Reduce heat to low.
Stir in garlic powder, seasoned salt, black pepper, and Worcestershire sauce.
Gradually add cheddar, stirring until melted.
Add cream cheese and stir until smooth (about 5 minutes total).
Mix cooked pasta with cheese sauce until well coated.
Transfer mixture to prepared baking dish.
In a bowl, mix panko, bacon, and Parmesan.
Sprinkle over mac and cheese.
Garnish with sliced jalapeños.
Bake uncovered for 30–40 minutes, until bubbly and golden.
Let rest 10 minutes before serving.