Preheat oven to 180C. Place beetroot on a double layer of foil, add half the olive oil, wrap with foil to seal. Roast for 1½ hours or until tender. Wrap garlic and remaining olive oil with foil, roast for final 40 minutes or until tender and slightly caramelised. Set beetroot and garlic aside to cool. Peel and quarter beetroot, peel garlic.
Blend garlic in a small food processor with the anchoves and cream until smooth. Blend in vinegar, extra virgin olive oil and stock powder.