Vanilla cream rolls

INGREDIENTS:

YIELD: 12 cannoncini
For the custard cream (crema pastiera):
3 egg yolks
3 tablespoons (30 gr) of all-purpose flour
1/2 cup (100 gr) of sugar
1 teaspoon of vanilla extract
8 oz (235 ml) of milk
For the cannoncini:
1 sheet of puff pastry, defrosted (about 8 oz, 225 gr)