3/4 cup poppyseeds
2 tablespoons unsalted butter
1/2 cup whole milk
1/4 cup sugar
1/4 cup honey
Juice and zest of 1 lemon
1/2 teaspoon coarse salt
1 large egg
1/2 cup all-purpose flour
1/2 cup light rye flour
1 cup kamut flour (I substituted whole wheat pastry flour for this)
2 tablespoons sugar
3/4 teaspoon fennel pollen (I swapped in 1/2 teaspoon ground fennel seeds)
1 1/2 teaspoons coarse salt
1/8 teaspoon freshly ground black pepper
1/2 pound (1 cup) unsalted butter, cut into 1/2 inch dice, chilled
1/2 pound cream cheese, at room temperature
2 tablespoons sour cream, at room temperature (I tossed some full-fat yogurt to drain in a dishtowel, which seems close enough for just a few tablespoons)
Egg wash (an egg beaten with a splash on milk and pinch of salt)
coarse sugar for sanding
To make the poppyseed paste: In a spice or coffee grinder, pulse the poppyseeds in batches for 15-20 seconds until broken up and powdery.
In a small saucepan, heat the butter, milk, sugar, honey, lemon juice and zest, and salt over a medium-low heat, stirring occasionally, until the butter melts and the sugar and honey dissolve, and it starts to barely steam.
In a medium bowl, whisk the egg. Gradually drizzle in the hot milk mixture, whisking constantly, until incorporated. Return the mixture to the saucepan, and heat over a medium-low heat, whisking constantly, until the mixture thickens enough to coat the back of a spoon, ~5-7 minutes (this won't be full-on pudding-type thickness, but it will thicken, like a custard sauce).
Remove from heat and whisk in the poppyseeds and salt, then let cool completely (it will thicken further as it cools — you can do this up to a week in advance).
To make the dough: In a food processor, combine the flours, sugar, fennel, salt and pepper. Pulse to combine. Scatter the chilled butter over the flour mixture, and pulse until the mixture is crumbly, with rice-sized pebbly bits. Transfer to the bowl of a stand mixer, add the cream cheese and sour cream, and mix briefly until a smooth dough forms (you can do this by hand as well, with a wooden spoon). Cover with plastic wrap and refrigerate until well chilled, at least 4 hours, or for up to 24 hours.
To make the cookies: On a lightly floured work surface, roll out the dough to a rectangle about 1/4-inch thick (if it's too square-like, you'll have a nice long spiral, but a greater chance that the whole mess will tip over, so aim for something long). Spread the poppyseed paste in a thin layer over the dough, leaving a 1/2-inch or so on the far long edge. Starting from the inside long edge, roll up the dough into a log, with the seam on the bottom. Wrap tightly in plastic wrap or parchment, and chill until firm, at least 2 hours or up to overnight.
When you're ready to bake, preheat the oven to 350° Fahrenheit. Line a sheet pan with parchment paper. Brush the log with the egg wash, and sprinkle generously with the sanding sugar. Cut the log crosswise into 1 1/2-inch thick pieces (you can go for 1-inch, which are more delicate, but a bit more inclined to flop over).
Transfer the cookies to the prepared baking sheet, leaving about 2 inches between cookies. Bake until golden brown, ~15 minutes. These cookies are best the first day or two.