In a small bowl or measuring cup, dissolve the yeast in 1/4 cup milk. If using instant yeast, do not dissolve it yet-- reserve.

In a large bowl, combine the yeast mixture with the remaining milk, butter, eggs, sugar, salt, and, if using, zest and/or mace. Blend in 1 1/2 cups flour. If using instant yeast, add it now.

Gradually add enough of the remaining flour to make a workable dough.

On a lightly floured surface or in a mixer with a dough hook, knead the dough until smooth and springy, about 5 minutes.

Place in an oiled bowl and turn to coat.

Cover with a kitchen towel or loosely with plastic wrap and let rise in warm, draft-free place until nearly doubled in bulk, 2 to 3 hours, or in the refrigerator overnight.

Punch down the dough, knead briefly, cover, and let rise in a warm, draft-free place until nearly doubled in bulk, about 1 1/4 hours.

Line a large baking sheet with parchment paper or lightly grease the sheet. Punch down the dough, knead briefly, divide in half, form into balls, and let stand for 10 minutes.

On a lightly floured surface, roll out the dough 1/2 inch thick. Cut into 2 1/2-inch rounds. Reroll and cut out the scraps.

Place on parchment paper-lined or greased baking sheets about 1 inch apart, cover with a towel or plastic wrap spritzed with cooking spray, and let rise at room temperature until nearly doubled in bulk, about 1 hour.

Position a rack in the center of the oven. Preheat the oven to 375°F (350°F for a convection oven). Using your thumb or the back of a spoon, press 1 large or 2 smaller deep indentations into the center of each round, leaving a 1/2-inch wide-rim. Brush the edges with the egg wash.

Spoon about 1 tablespoon topping into the indentation and, if using, sprinkle lightly with the posipka.

Bake until golden brown or the center of the dough registers about 180°F on an instant-read thermometer, about 12 minutes. Transfer to a wire rack and let cool.

Kolache are best eaten on the same day they are made, but can be covered with plastic wrap and stored at room temperature for up to 2 days on in freezer for up to 3 months.

VARIATIONS:

For 12-inch round cakes: On a lightly floured surface, roll each half into a 12-inch round. Place on the prepared sheet, leaving several inches between each round. Cover with a towel or plastic wrap spritzed with cooking spray and let rise at room temperature until nearly tripled, about 1 1/2 hours.

Position a rack in the center of the oven. Preheat the oven to 375°F (350°F for a convection oven).

With a large spoon or your thumb, press 6 evenly spaced deep large triangular indentations into the dough, leaving a 1/2-inch-wide outer rim and between the indentations. Brush the edges with the egg wash.

Fill each section with about 1/3 cup of 3 or 6 different toppings. If using, sprinkle lightly with the posipka.

Bake until golden brown or the center of the dough registers about 180°F on an instant-read thermometer, 15 to 25 minutes. Transfer to a wire rack and let cool.