Divide ground chuck into 8 even sections, form 2 inch diameter slider patties. Set aside.
In a separate bowl, melt butter. Add in garlic, paprika, cayenne pepper, pepper flakes, lemon juice, parsley, salt, pepper, and mustard. Whisk until well combined.
Grill the sliders. Baste the patties with the butter using a basting brush.
Once sliders reach internal temp of 145ºF, remove from grill. Form sliders with buns (toast if desired), pepper jack cheese, and jalapeño. Enjoy!