STEAK WITH ANCHOVY BUTTER

½ x 650g pack charlotte potatoes, halved or quartered • 2 rosemary sprigs, plus • 1 tsp finely chopped leaves • 3 garlic cloves, 2 peeled and bashed, 1 crushed • 4 tsp olive oil • 2 x 150g sirloin steaks • 100g Lurpak Slightly Salted Butter, softened a little • 10 anchovy fillets in olive oil, drained and roughly chopped • 200g Tenderstem broccoli spears