Begin by peeling and chopping the potatoes into evenly sized chunks. Place them in a large pot of salted boiling water to cook until they're exceptionally tender — this ensures a smooth, creamy mash. Drain thoroughly. Using a sturdy masher, coarsely crush the potatoes along with at least 2 tablespoons (30 ml) of butter, allowing the richness to infuse the spuds. Next, use an electric mixer to whip in the milk until the mixture becomes velvety smooth. Season generously with salt and pepper to enhance the flavor, then set this luscious mashed potato aside. Preheat your oven to 190 °C (375 °F), positioning the rack in the middle to ensure even heat distribution during baking. In a large skillet over medium heat, melt the remaining butter and sauté the finely chopped onion until it turns soft and golden, releasing its sweet aroma. Add the minced beef, cooking until it browns beautifully and slightly crisps on the edges, seasoning with salt and pepper to taste. Once perfectly cooked, remove from heat. Lightly press the savory meat mixture into the bottom of a 20-cm (8-inch) square baking dish, creating an even base. Spoon the creamed corn gently over the beef, spreading it out with care to maintain the layers. Top the dish with the creamy mashed potatoes, smoothing the surface with the back of a spoon or spatula. Sprinkle a dusting of vibrant paprika and fresh parsley over the top for a pop of color and subtle flavors. Bake in the preheated oven for about 30 minutes, allowing the layers to meld and the top to develop a light golden crust. For a finishing touch, place the dish under the broiler briefly to achieve a beautifully browned and slightly crispy topping—keep a close watch to prevent burning. Once done, let the Pâté Chinois cool for 10 minutes before serving; this allows the layers to set for easy slicing and enhances the flavors. Tip: For an extra rich mash, consider warming the milk before mixing it in. Also, if preferred, add a pinch of nutmeg to the potatoes for a subtle depth of flavor.