Preheat the oven to 425°F and line a large sheet pan with parchment paper.
Toss halved baby potatoes with 2 tablespoons olive oil, salt, and pepper, then roast cut-side down for 18 minutes.
Toss broccoli with remaining olive oil, salt, and pepper, add it to the sheet pan, and roast 10 minutes more.
Pat salmon dry, season lightly, and sear in a hot skillet for 3 to 4 minutes per side.
Reduce the heat, melt butter, cook garlic briefly, then stir in broth, cream, lemon juice, zest, and Dijon.
Return salmon to the skillet and spoon sauce over the fillets until the salmon is warm and cooked through.
Serve the salmon with crispy potatoes and broccoli, spoon sauce over the plate, and finish with chopped parsley.