Preheat the oven to 350°F. Stir together all of the ingredients for the meatloaf and season the mixture with salt & pepper. Grease the 3 heat-resistant bowls with vegetable oil, then divide the meatloaf among all 3 of the greased bowls. Press the meatloaf firmly into the sides of the bowls, transfer the bowls to the oven, and bake the meatloaf domes at 350°F for 30–40 minutes. Once they're done baking, let the meatloaf domes cool, but keep the oven warm for the next steps.
Tear up the slices of white bread and use the bottom of a tall glass to firmly press the bread down into the bottom of the 6-inch springform pan.
Melt the butter in a saucepan, then gradually add in the flour, stirring continuously. Let the butter mixture heat up for 2–3 minutes, but don't let it brown. Add in the milk and bring the sauce to a boil, still stirring constantly. Once the sauce starts to thicken, add in the cheese and stir the mixture until it has melted. Season the béchamel sauce with salt.
Sauté the diced vegetables in a small amount of vegetable oil and season them with salt & pepper. Pour ½ of the béchamel sauce into the frying pan with the mixed vegetables and stir everything together thoroughly.
Spoon some of the mixed vegetables into each of the 3 meatloaf domes and stack them one on top of another, making sure to keep the largest meatloaf dome inside of its bowl.
Transfer the bread base to the top of the stacked meatloaf domes.
Grate chilled butter on top of the bread base and spread it around evenly. Transfer the meatloaf dome cake to the oven and bake at 350°F for 30–40 minutes.
For the flower decorations, use a heart-shaped cookie cutter to cut hearts out of the skin of the zucchini, then cut them in half. Use a flower-shaped cookie cutter to cut small flowers out of the other vegetables. Briefly sauté the vegetable flowers in some vegetable oil and soak the chives in hot water. Once it's done baking, carefully flip the meatloaf dome cake over onto a plate and heat up the remaining béchamel sauce. Pour the béchamel sauce over the meatloaf dome cake, then decorate it with vegetable & peppercorn flowers, zucchini leaves, and chive stems.