Preheat oven to 425°F and let it reach high temperature for about 15 minutes.

Trim outer leaves, rinse, and pat radicchio heads dry. Slice each head into 1-inch wedges. Keep the core intact.

In a large bowl, toss radicchio wedges with olive oil, salt, and black pepper until evenly coated.

Arrange wedges cut-side down on a parchment-lined baking sheet. Roast for 20–25 minutes until tender and golden brown.

In a small saucepan over low heat, combine honey, balsamic vinegar, and minced garlic. Stir until heated through and slightly thickened.

Spoon the warm honey balsamic glaze over the roasted radicchio wedges immediately after removing from the oven.

Transfer to a serving platter, garnish with thyme, toasted nuts, and shaved Parmesan. Serve warm or at room temperature.