Tender, buttery brioche is a natural partner for lemon, and lemon and blueberry have been bringing out the best in each other forever. Bake as buns, sporting a bright blue swirl of blueberry-flavored cream cheese inside. Or turn this combination into a stunning lemon blueberry babka (see "tips," below).
To make the dough: Weigh your flour; or measure it by gently spooning it into a cup, then sweeping off any excess. Mix together all of the ingredients —in a stand mixer or bread machine — to form a smooth, shiny dough. This can take up to 15 to 20 minutes when kneading at medium speed in a stand mixer; we don’t recommend trying to knead this by hand.
When the dough is developed (it will be very soft), transfer it to a greased bowl, cover, and let rise for 1 hour before refrigerating for at least 2 hours, or up to overnight.
To make the filling: Whisk together the confectioners’ sugar, blueberry powder, and Instant ClearJel.
Place the cream cheese and butter in a mixing bowl and beat at low speed until smooth. Add the blueberry mixture; scrape the bowl and mix for 20 seconds more. Mix in the lemon juice. Cover and set aside.
Grease the wells of a muffin tin.
To shape the buns: Turn the chilled dough out and roll it into a 12" x 18" rectangle, with the long side facing you. Spread the filling on the bottom half of the rectangle, all the way out to the short sides. Sprinkle evenly with lemon crumbles, pressing gently to adhere.
Fold the uncovered half of the dough down and press gently to seal. Cut into 12 strips, each 1 1/2" wide. Roll each strip into a spiral and place into a well of the prepared pan, cut side up. Repeat until all the strips are used.
Cover the pan and let the buns rise until they're puffy looking, about 1 1/2 hours. Toward the end of the rising time, preheat the oven to 350°F.
Uncover the buns and bake them for 23 to 25 minutes, until golden brown. Remove them from the oven and cool in the pan on a rack for 15 minutes before tipping them out of the pan and returning to the rack to finish cooling.
To make the glaze: Heat the lemon crumbles and half-and-half or milk at 50% power in a microwave in 30-second bursts; stir until melted and smooth. Drizzle the glaze over the cooled buns.
Storage information: Store leftovers, well wrapped, at room temperature for up to three days; freeze for longer storage.
To make a lemon blueberry babka: Prepare the dough and filling through step #6, above, spreading the filling all the way to the edges of the dough but leaving a 1" bare margin on one short end. Starting with the filling-covered short end, roll the dough into a cylinder and pinch the seams to seal. Use a sharp knife to cut the cylinder lengthwise; turn the cut sides up to show the filling. Twist the two pieces into a braid, keeping the cut sides up and tucking the ends underneath. Put the babka into a greased 9" x 5" loaf pan or tea loaf pan. Cover and let rise until puffy looking, 60 to 90 minutes. Uncover and bake the babka for 45 to 55 minutes, tenting as necessary to prevent overbrowning, until the center reads 190°F when measured with a digital thermometer. Remove the babka from the oven and cool it in the pan on a rack for 20 minutes before turning it out of the pan onto the rack to cool completely. Drizzle the completely cooled babka with the glaze.
