Grate the cleaned beetroot and carrot. In a bowl stir them with the salt, sugar and pepper to taste, pour in the vinegar and olive oil and stir well.
Put the salad in the refrigerator for 30 minutes. Then beat the cream (if it seems like it's too much, use less cream), mayonnaise and walnuts together.
Pour the mixture on the salad and stir well. Leave in the refrigerator for 30 minutes.
Serve with some coarsely chopped parsley, if desired.