Multi-color cauliflower gratin served with a skirt steak roulade

Yes, cauliflower served with a steak, and not the reverse, as the cauliflower gratin was the real star of this dish. Not that the skirt steak, marinated in green tomato salsa, rolled on itself, and rapidly/high temperature seared to obtain a rare doneness (this is the best way to eat meat like skirt or hanger steaks) was bad. It was even delicious with its sauce made from the meat trims, with shallots, Cognac, balsamic, soy sauce and red Bordeaux wine.
But this multi-color cauliflower gratin was really to die for. Cauliflower gratin was one of my Mom's (many) signature dishes. When we were kids, my brothers and I didn't like cauliflowers. I don't know if this is because our palates changed or because the vegetable "engineering" has made "progess" since then, probably both, but the truth is that I found the sulphur taste of the cauliflower particularly unpleasant. So my Mom's trick was to serve it as a gratin with a Béchamel sauce to hide this "vomit" taste. She was doing the same thing to mask the endive bitterness!
Things have changed, since I love cauliflower now, in all its states: raw with just a homemade mayonnaise, roasted, BBQ'd, gratinéed, pickled... Here, I revisited a little bit my Mom's gratin, using those beautiful multi-color cauliflowers from the farmers'market: purple, white, light green baby cauliflowers that the vendor was smart enough to sell as a batch, plus a bigger, unterstand "normal", solid green romanesco. I also built the gratin like I would build a classical fruit tart, with a crust, a cream and the fruits on the top. What is quite funny is that I hardly bake. In fact, I am just starting. Then, I watch a lot of French pastry programs and if don't really put in practice what I learn there, it inspires me... for my cooking!!! Well, truly, a fruit tart is by far not the most complicated pie to make.
For this cauliflower pie, the pie "crust" was a slice of romanesco (it would be called a steak in other circumstances), slowly seared in a foamy butter with herbs and garlic, and on which I pour a little bit of egg white to fill up the insterstices due to the star shape of this special "crust". The cream was a sauce Mornay (i.e. a Béchamel with grated gruyère and egg yolks), and the topping was the cauliflower florets that had been previously blanched and that I studded in the Mornay "cream". A round cookie cutter helped me to mount the "pies" that were baked at 400F for 15 minutes, before passing 6/7 minutes under the broil (400F).
That was absolutely fabulous!