Preheat the oven to 350°F Line one 12-cup muffin tin with paper muffin liners.
In a food processor, combine ricotta cheese, cottage cheese, sour cream, egg, vanilla, sugar and flour; purée until smooth. Divide the mixture among the prepared muffin cups. Place a dollop of strawberry jam in each muffin cup and use a butter knife to swirl it around gently.
Set the muffin tin in a larger pan. Pour enough hot water into the pan to come halfway up the sides of the muffin cups.
Bake in the centre of the oven for 20 to 25 minutes or just until the muffins are set.
Remove the muffin tin from its water bath. Let the tin cool on a wire rack. Chill.