In the bowl of a stand mixer or large bowl, combine all the ingredients for the dough and mix and knead until the dough is soft and smooth. Lightly oil a large bowl and shape the dough into a ball. Place it in the bowl and cover with a clean dish towel for 1 1/2 hours to rise, or until the dough is almost doubled.
While the dough is proofing, make the filling: Take the butter out of the refrigerator to soften. Set aside.
In a small bowl, combine the sugar, lemon zest, powdered vanilla (if using) and cardamom. Stir together until it's well combined and is the consistency of wet sand. Set aside.
Cut a piece of parchment paper to fit the bottom of a 13 x 9" pan or two 8" cake pans. Spray the pans with vegetable spray and place the parchment on the bottom of the pan, pressing so it sticks. Spray the bottom of the parchment with vegetable spray and set aside.
When the dough has proofed, roll it out into a rectangle measuring 11 x 20 inches. Spread the softened butter over all of the dough except for one inch running along the long edge.
Sprinkle the lemon sugar over the butter and spread over the dough evenly. Spread the lemon sugar evenly with the strawberries and blueberries.
Starting with the long edge that Is buttered and sugared, roll the dough into a pinwheel. Use a sharp serrated knife to cut the dough in half at the center. Divide each of those halves into 6 to 8 equal pieces. Do the same with the other half of dough and transfer the buns to the prepared pan
If there's any lemon sugar that falls out of the dough while rolling and shaping, sprinkle it over the rolls. Let the rolls rise a second time, about an hour or until they are very light and puffy.
Preheat the oven to 350°. Bake the rolls for 20-25 minutes or until lightly golden brown.
FOR THE CREAM CHEESE GLAZE:
In a medium bowl, beat the cream cheese until smooth and creamy, add the lemon juice and confectioner's sugar and beat until very smooth. Set aside.
When the rolls are done, let them cool in the pan for 10-15 minutes, then top with cream cheese glaze, spreading evenly over the rolls. Enjoy!
Notes
For metric conversion use one large egg + enough water to measure 236 ml.