In a pot with plenty of cold water, submerge the alcachofas, add the lemon slices, and bring to a boil over high heat. Reduce the heat and continue cooking until the artichokes are well cooked, meaning that when you carefully pull one of the leaves, it detaches easily.
Drain the artichokes and let them cool slightly.
Using a spoon, scrape the meat from the artichoke leaves to collect the pulp.
Clean the artichoke bottoms as well, chop them finely, and mix them with the rest of the collected meat.
Set the artichoke mixture aside.
Preheat your oven to 400°F (200°C).
Heat a skillet with a little oil, add the onion, and cook over low heat, stirring occasionally, until the onion is soft and translucent, about 5 minutes; if it starts to brown, add a little water to lower the temperature.
Mix the artichoke meat with the cooked onion.
Add the rest of the ingredients: heavy cream, mustard, queso mantecoso, and parmesan cheese. Season with salt and pepper and stir everything together well.
Transfer the mixture to oven-safe dishes, using either one large dish or several small ones, and bake for 15 minutes or until the top is lightly browned.
Serve your artichoke dip immediately with crackers or toast and enjoy! ¡A disfrutar!