Melt butter in a small saucepan over medium heat. Add flour and whisk for 1 minute. Whisk in milk and bring to a simmer. Once thickened, turn off heat and add cheddar cheese. Whisk until completely smooth. Add garlic and cayenne and mix to combine. Set aside.

Heat pretzel nuggets according to package directions. Arrange on a serving dish.

Drizzle 3/4 cup of cheese sauce over the pretzel nuggets and reserve the remaining for dipping. Sprinkle tomato, red onion and jalapeno over pretzel nuggets. Garnish with chopped cilantro and place a scoop of sour cream on top. Enjoy immediately.