How to Make It
In a small saucepan, melt the butter. Add the garlic, anchovies, 1/4 cup of the olive oil and 1 teaspoon of the lemon zest and cook over moderately low heat, stirring occasionally, until the garlic is softened and the anchovies are melted, about 10 minutes. Season with salt and pepper. Remove the bagna cauda from the heat and keep warm.
Meanwhile, in a large pot of boiling salted water, blanch the cauliflower wedges until crisp-tender, about 3 minutes. Drain the cauliflower and transfer it to a paper towel–lined plate; pat thoroughly to dry.
In a large skillet, heat the remaining 2 tablespoons of olive oil until shimmering. Add the cauliflower and cook over moderately high heat, turning once, until cooked through and golden brown on both sides, 10 minutes. Season with salt and pepper. Transfer the cauliflower to plates and spoon some of the bagna cauda on top. Top with the parsley and the remaining 1 teaspoon of lemon zest and serve with the remaining bagna cauda.