Preheat oven to 450°F. Line a large baking sheet with foil; brush foil with half the melted butter. Toss onion wedges with remaining butter, thyme, salt and pepper until all onions are coated. Spread in a single layer on baking sheet and drizzle with vinegar; cover tightly with foil. Roast for 20 minutes. Rotate baking sheet so the side facing the back of the oven is now facing the front and roast 20 minutes longer. Remove foil and gently shake pan, loosening the onions from the foil. Roast for 15 minutes longer or until onions are soft and have brown edges. To prepare dressing, place vinegar, salt, garlic and shallots in a medium bowl and let steep for 5 minutes. Stir in mustard, Amaz!ns™, capers, tarragon, red onion and pepper. Slowly stream in olive oil, whisking constantly to emulsify vinaigrette. Preheat an outdoor grill or grill pan to medium-high. Trim escarole leaving the heads intact; swish in water and pat dry. Coat lightly with cooking spray and grill for 5 minutes, turning once, until wilted and grill marks appear. Season with salt and pepper to taste. Tear into bite size pieces and gently toss with roasted red onions and 1/2 cup vinaigrette. Arrange on a platter and sprinkle with ricotta salata and almonds. Drizzle with additional vinaigrette, as desired, and serve.