Trim excess fat from the roast and cut into 8 large pieces. Pat dry and season liberally with salt and pepper.

Add vegetable oil to a large, heavy pan, and heat over MED-HIGH heat. Once oil is shimmering, add half the meat to the pan, leaving room in between each piece. Let meat sear on one side without moving it for several minutes. If you try to flip the meat and it sticks to the pan, let it cook a little bit longer. It will release on it's own when it's ready to flip.

Sear all sides of the meat, remove to a plate, and repeat with remaining half of meat.

Add all meat pieces to the bottom of slow cooker, making sure to add any drippings from the plate, that's extra flavor!

Add vinegar, garlic, cumin, oregano, cloves, pepper, salt, beef stock, lime juice and chipotle chiles to a blender and puree until smooth. Stir in drained green chiles.

Pour sauce over meat in slow cooker, turn to fully coat meat in the sauce, then add bay leaves.

Cover, and cook on LOW for 10 hours (or HIGH for 6 hours).

Remove bay leaves.

Remove meat to a large bowl and shred. Return meat to the slow cooker and heat on LOW in the sauce, uncovered, for 10 minutes.

Prepare ingredients and set aside.

Add half and half to a saucepan and heat over MED heat until JUST simmering.

Reduce heat to LOW and stir in 1/3 cheeses, mixing well until smooth. Repeat with another 1/3 of the cheeses, and then a final time with the remaining 1/3.

Stir until cheeses are completely melted, then stir in jalapenos, cumin, nutmeg, red pepper flakes, salt and pepper.

If cheese starts to get too thick or seize up, stir in additional half and half until it reaches desired consistency.

To test to see if the oil is ready, rip off a small piece of flour tortilla and toss it in the oil... it should bubble and slowly turn golden brown.

Lay out a flour tortilla, add several spoonfuls of shredded beef barbacoa to the tortilla in a horizontal line, leaving an inch or so of border on the sides.

Top beef with a handful of Queso Fresco cheese.

Roll the tortilla as you would a burrito, up from the bottom over the meat and cheese, fold the sides in, then continue rolling upward.

Place chimichanga seam side down in the oil and let it fry for about 1-2 minutes, then carefully flip it over and fry an additional minute or so.

Remove to a paper towel lined plate to drain and cool.

Repeat with remaining chimichangas.

To serve, top chimichanga with queso, queso fresco cheese, minced cilantro, pico de gallo and diced avocado.