In the bowl of a stand mixer, whisk together 3 1/2 cups all-purpose flour, 2 1/4 teaspoons instant yeast, 2 1/4 teaspoons instant yeast, and 1/2 teaspoon table salt. In a small bowl or large measuring cup, whisk together 1 cup warm water, 1/4 cup canola oil, and 2 large eggs. Pour the egg mixture into the flour mixture, and lightly stir.
Set the bowl into the stand mixer fitted with a dough hook. Turn the mixer on low speed, and mix until all of the flour is incorporated, about 5 minutes, turning off the mixer to scrape down the sides periodically. If the dough is still sticking to the sides of the bowl after all of the flour has been mixed in, add up to 1/2 cup more flour 1 Tablespoon at a time, making sure that all of the previous flour has been incorporated before adding more. Continue mixing until the dough pulls away from the sides of the mixer, but sticks to the bottom, about 5-10 more minutes.
Turn the dough onto a lightly floured surface, and gently knead 5-10 times until it forms a ball. Place the ball into an oiled bowl. Cover with plastic (or a lid) and let rise for 1-1 1/2 hours until the dough is doubled in size.
Filling
While the dough is rising, mix up the filling. Stir together 1 cup dry curd cottage cheese, 1 Tablespoon heavy cream , 1-2 teaspoons minced fresh dill, 1/2 teaspoon table salt, and 1/4 teaspoon freshly ground black pepper in a medium bowl. Set aside in the fridge until ready to use.
For the Buns
Prepare two baking sheets by lining them with parchment paper or silicone baking mats. Set aside. Turn on the oven to 350°F
Using a kitchen scale, measure out 1 ounce (28g) of dough. Work with one piece of dough at a time, keeping the remaining dough covered. Roll the dough into a ball, then use a rolling pin to roll and stretch the dough into a roughly 3" round. Note that the dough will be sticky, and it's helpful to work on a lightly floured surface, keeping additional flour on hand as needed.
Holding the dough in the palm of your hand, carefully place about 2 teaspoons of the cottage cheese filling in the center with the other hand. Put the spoon down, and carefully pull the edges of the dough around the filling, pinching to seal it completely. Place the filled dough ball on one of the prepared baking sheets, seam side down. Cover gently with a clean towel while you continue.
Repeat the above two steps with the remaining dough. Allow the buns to rise a little longer on the baking sheet (up to about 10-15 minutes after you've added the last bun to the baking sheet. When you're ready to bake the buns, very gently and very lightly brush the tops with melted butter.
Bake the buns until the tops are golden brown, about 25 minutes, turning the sheets halfway through baking. Note that I find it easier to bake the sheets one at a time, since it takes so long to form and stuff the buns, that the first ones you make are already risen and ready to bake well before the last ones.
To serve immediately: Stir together 1/2 cup heavy cream, 1 Tablespoon minced fresh dill, 1/4 teaspoon table salt, 1/4 teaspoon freshly ground black pepper, and any leftover melted butter you have from brushing the buns before baking. Heat the mixture in the microwave until hot, about 30-60 seconds. Transfer the buns to a serving platter or bowl, and pour the hot cream sauce over them. Serve immediately.
To serve later: Let the buns cool to room temperature then transfer to a large zipper bag and store in the fridge. When you want to serve them, heat the oven to 325°F. Transfer the buns to a large casserole dish or a 9x13" baking dish (separate the buns into two smaller dishes if needed). Whisk together 1/2 cup heavy cream, 1 Tablespoon minced fresh dill, 1/4 teaspoon table salt, and 1/4 teaspoon freshly ground black pepper to make the dill cream sauce. Pour the sauce over the buns (there is no need to heat it this time). Cover the dish with a lid or with aluminum foil, and bake for 20-30 minutes until hot. Serve immediately.