Preheat your oven to 400 degrees F. Wrap each beet individually in aluminum foil and place them on a rimmed baking sheet. Roast for 50 to 60 minutes, depending on size, until a paring knife slides into the center without resistance. Pull them out and let them cool in the foil for about 15 minutes. Put on kitchen gloves before you unwrap them, because the juice stains instantly.

While the beets roast, heat 1 tablespoon of olive oil in a large skillet over medium-low heat. Add the sliced onions and a pinch of salt. Cook, stirring every 5 minutes or so, for 35 to 40 minutes until they are deep golden brown and very soft. They should smell sweet and look almost jammy. Stir in the balsamic vinegar and thyme, cook 1 more minute, then take the pan off the heat.

Slip the skins off the cooled beets while still slightly warm. They should peel right off with your fingers. Slice the beets into rounds about 1/4 inch thick. Season the slices lightly with salt and pepper and a drizzle of the remaining olive oil.

Lower the oven temperature to 375 degrees F. Spread the caramelized onions in an even layer across the bottom of a lightly oiled shallow baking dish. Layer the beet slices over the onions, overlapping them slightly like shingles. Drop small crumbles of goat cheese evenly across the top.

In a small bowl, stir together the panko, chopped walnuts, parsley, melted butter, and garlic powder until the crumbs are evenly coated. Scatter this mixture over the goat cheese layer in an even, loose layer.

Bake uncovered at 375 degrees F for 20 to 25 minutes, until the breadcrumb topping is golden brown and the edges of the beets are beginning to look a little caramelized around the dish. Let it rest for 5 minutes before serving. Serve warm with a simple green salad.