Make the knots: Put the melted butter in a bowl. Whisk the granulated sugar and espresso powder in another bowl.
Butter a 12-cup muffin pan. Divide the dough into 12 pieces; roll each piece into an 8-to-9-inch rope. Dip 1 piece of dough in the butter, letting the excess drip off, then roll in the espresso sugar. Tie the dough into a knot. Place in a muffin cup with one end of the knot facing up. Repeat with the remaining dough. Let rise, uncovered, in a warm place until doubled in size, about 1 hour, 15 minutes.
Preheat the oven to 350 degrees F. Bake the knots until puffed and golden brown, about 30 minutes. Transfer to a rack and let cool 10 minutes in the pan.
Meanwhile, make the glazes: Whisk 1 cup confectioners' sugar and the espresso powder in a medium bowl; add 1/4 cup heavy cream and whisk until smooth, adding more cream if necessary. In a small bowl, whisk the remaining 1/4 cup confectioners' sugar with the remaining 2 tablespoons cream until smooth. Transfer the white glaze to a resealable plastic bag.
Remove the knots from the pan and dip the tops in the espresso glaze; let set 5 minutes. Snip a small corner of the bag with the white glaze and pipe over the knots.
Basic Sweet-Roll Dough:
Yield:Photograph by Johnny Miller
Warm 1/2 cup water and the milk in a saucepan over low heat until a thermometer registers 100 degrees F to 110 degrees F. Remove from the heat and sprinkle the yeast on top, then sprinkle with a pinch of the sugar; set aside, undisturbed, until foamy, about 5 minutes.
Whisk the melted butter, egg yolk and vanilla into the yeast mixture until combined. In a large bowl, whisk the flour, the remaining sugar, the salt and nutmeg. Make a well in the center, then add the yeast mixture and stir with a wooden spoon to make a thick and slightly sticky dough. Turn out onto a floured surface and knead until soft and elastic, about 6 minutes. Shape into a ball.
Brush a large bowl with butter. Add the dough, turning to coat lightly with the butter. Cover with plastic wrap and let rise at room temperature until the dough is doubled in size, about 1 hour, 15 minutes.
Turn the dough out of the bowl and knead briefly to release excess air; re-form into a ball and return to the bowl. Lightly butter a large piece of plastic wrap and lay it directly on the surface of the dough. Cover the bowl tightly with plastic wrap and refrigerate at least 4 hours or overnight.