In a large bowl, whisk together the flour and salt. Cut the chilled butter and shortening into small cubes and add to the flour mixture. Using a pastry cutter, two knives, or your fingertips, work the butter and shortening into the flour until the mixture resembles coarse breadcrumbs with pea-sized pieces of fat still visible—this creates the flaky texture we want. Add the water a little at a time, mixing gently with a fork until the dough just comes together. Form it into a disk, wrap in plastic wrap, and refrigerate for at least 30 minutes while you prepare the filling. I find that chilling the dough makes it much easier to roll and helps it hold its shape during baking.

While the dough chills, prepare the filling. Dice the jalapeno peppers into small pieces, removing seeds if you prefer less heat. In a medium bowl, beat the cream cheese until it's soft and spreadable. Add the seasoning, pepper, onion powder, and ground cumin to the cream cheese, stirring until well combined. Fold in the shredded cheddar cheese, diced jalapenos, and chopped brisket, mixing until everything is evenly distributed. The cream cheese acts as a binder and adds richness to the filling, while the warm spices complement the savory brisket beautifully.

Preheat your oven to 400°F. Remove the chilled dough from the refrigerator and place it on a lightly floured surface. Roll the dough out to about 1/8-inch thickness. Using a 4-inch round cutter or the rim of a glass, cut circles from the dough, re-rolling scraps as needed. Place 2 to 3 tablespoons of the brisket filling mixture from Step 2 onto one half of each dough circle, leaving about 1/2-inch border around the edge. I like to keep the filling generous but not overflowing, as it helps the empanadas stay sealed during baking.

Fold each dough circle in half over the filling, creating a half-moon shape. Press the edges firmly with the tines of a fork to seal them completely—this not only seals the empanada but creates a decorative pattern. In a small bowl, whisk together the egg and 1 tablespoon of water to make an egg wash. Brush the top of each sealed empanada generously with the egg wash, which will give them a beautiful golden-brown appearance and help them crisp up in the oven.

Arrange the prepared empanadas on a baking sheet lined with parchment paper. Bake in the preheated 400°F oven for 20 to 25 minutes, until the pastry is golden brown and crispy. The empanadas should be puffy and the filling hot throughout. Remove from the oven and let cool for 2 to 3 minutes before serving—this allows the filling to set slightly so it doesn't spill out when you bite into it.