Pre-heat oven to 450 degrees and line two baking sheets with foil.
Divide the cauliflower between both baking sheets (you want it in a single layer) and drizzle each sheet with 1 tablespoon of the olive oil, 1/2 teaspoon of the salt and 1/4 teaspoon of the pepper. Mix well with your hands to coat and bake in oven until caramelized and golden brown, 20-25 minutes.
In a small bowl, whisk together the jalapeño caper vinaigrette by combining the remaining 2 tablespoons olive oil, 1 teaspoon salt and 1/2 teaspoon pepper with the parsley, garlic, jalapeño, lemon juice and capers.
Remove cauliflower from the oven and pour into a large serving platter. Drizzle with the jalapeño caper vinaigrette to serve.