1. Cream together butter and cream cheese with the paddle attachment of a standing mixer until well blended. Add the ½ cup sugar, salt, and vanilla and beat on medium low speed until blended. Beat in egg yolks one at a time, scrape down the mixer with a spatula, then add flour and mix on low speed to form a soft dough. Turn the dough out onto a large piece of plastic wrap and pat into a 6” circle. Chill for at least one hour or up to overnight, until firm.
2. Preheat oven to 350. On a lightly floured surface, roll the rugelach dough out to approximately ¼” – about a 10” circle. Spread Bonne Maman Blueberry Intense Fruit Spread out in a thin layer, leaving 1/8” of the outer edge clean. Cut the circle into 16 thin wedges. Starting at the wide edge, roll each wedge tightly to resemble a croissant, and place seam side down on a parchment lined or greased baking tray. Brush rugelach with milk and sprinkle with cinnamon sugar. Bake until deep golden brown – about 24 minutes. Allow to cool, rugelach are best served they day they are baked although can be stored in an airtight tin for up to 3 days or frozen, well wrapped, for up to a month.
3. Do ahead: The unbaked, assembled rugelach can also be frozen for up to 3 months and baked as needed.