Preheat the oven to 350º. In a small bowl, combine the bread and milk, and let soak for 20 minutes. Squeeze the bread to drain any excess milk, then transfer to a large bowl.
Meanwhile, in a small heatproof bowl, cover the wood ear mushrooms with boiling water and let sit until rehydrated, 15 minutes. Drain and julienne, then transfer to the bowl with the bread.
In a 12-inch skillet, heat the olive oil over medium-high heat. Add the onions and cook, stirring occasionally, until lightly caramelized, 5 to 7 minutes. Let cool completely, then transfer to the bowl with the mushrooms and bread.
To the large bowl, add the ground pork and beef, chorizo, 1 cup of the grated cheese, the olives, pine nuts, almonds, lemon juice, salt, pepper, lemon zest and 3 of the eggs. Using your hands, mix the meat loaf until well incorporated, then transfer to a 12-inch cast-iron skillet.
Press the meat loaf into a ring shape, making sure the top of the meat loaf is even with the rim of the pan and that there is a 4-inch hole in the center. Beat the remaining egg and brush the meat loaf liberally with half. Sprinkle the remaining ½ cup of grated cheese over the meat loaf and brush with the remaining egg. Lay the bacon slices around the meat loaf, starting in the center and draping out to the edge, like the hands of a clock.
Place an ovenproof 4-inch bowl in the center of the meat loaf, making sure the rim sits underneath the top of the meat loaf, so it can collect excess fat. Place the skillet on a parchment-lined baking sheet and bake until an internal temperature of 150º is reached according to a instant-read thermometer, 1 hour to 1 hour and 10 minutes.
Let cool for 20 minutes, then remove the bowl and discard any collected fat. Slice the meat loaf and serve.