Grease a large bowl.

In a large liquid measuring cup, combine the eggs, milk, and honey.

In the bowl of a stand mixer fitted with a paddle, mix the flour, yeast, and salt and stir on low to combine. Add the egg mixture and mix on low to combine. With the mixer on low, add the butter, one piece at a time. When all the butter has been added, increase the speed to medium and beat the butter into the dough, until all the little butter pieces are incorporated, 1 minute. Transfer the dough to the prepared bowl. The dough will be very sticky and you will need a spatula to scrape the dough into the bowl.

Cover the bowl with plastic wrap and let rise for 30 minutes. Place your fingers or a spatula underneath the dough and gently pull the dough up and fold it back over itself. Turn the bowl and repeat this folding again. Continue 6 to 8 more times, until all the dough has been folded over on itself. Re-cover the bowl with plastic and let rise for 30 minutes. Repeat this series of folding 3 more times, for a rise time of 2 hours and a total of 4 foldings. Tightly cover the bowl with plastic wrap and refrigerate overnight or up to 72 hours.

Place the rhubarb, blackberries, sugar, salt, and vanilla bean into a medium pan and simmer over medium-low heat for about 30-40 minutes, stirring often, until the rhubarb and blackberries have broken down and the jam has thickened. The jam will cling to a wooden spoon when it is done. Remove from the heat and allow to cool to room temperature. Remove the vanilla bean and discard, then refrigerate the jam until ready to use. (Taste your jam – if it is a little flat, you can add a squeeze or two of lemon juice – about 1/2 teaspoon at a time, until it brightens the flavor.)

In the bowl of a stand mixer, combine the all-purpose flour, sugars, almond flour, salt, and cinnamon on low. With the mixer on low, add the butter, one tablespoon at a time, until the mixture comes together but still is quite crumbly.

In a small bowl, mix the cream cheese, milk, salt, and vanilla until smooth. Add 1 cup of the powdered sugar and mix again until smooth. If the mixture is too thin, add more powdered sugar until the desired consistency is reached.

Line a half sheet pan with parchment paper (the photo shows the 10-inch Mauviel pan – if you use something similar, generously grease the sides and bottom of the pan with butter).

On a lightly floured surface, fold the dough over 3-4 times and then form it into a ball. Let the dough rest for 15-20 minutes.

Roll the dough into a 1/4-inch thick rectangle. Brush the entire surface with 2 tablespoons melted butter. Start with 1/2 cup of jam, and spread the jam over the dough. If more jam is needed, add more until there is a thin layer over the dough (you don’t want too much jam, or the next steps will be extra messy).

Roll the dough up, starting at the short end. Using a sharp kitchen knife or scissors, cut the log into 12 equal pieces.

Set the buns in the prepared pan, 1 1/2 to 2-inches apart. Loosely cover the buns and let them rest between 1 1/2 to 2 hours, until they have almost doubled in size. (You can set these up the night before and let them rest overnight in the refrigerator. In the morning take them out and let them sit on the counter for about 45 minutes to an hour.)

Adjust an oven rack to the middle position, and heat the oven to 350F. Generously cover the tops of the buns with the streusel before putting into the oven, gently pressing the streusel into the buns (there will be some streusel left over).