Combine 2 cups flour, 1/2 cup sugar, yeast, and salt in a large bowl of a stand mixer fitted with the paddle attachment.

Heat milk, water, and 4 tablespoons butter in a medium saucepan over low heat until warm to the touch. Pour into the flour mixture; beat on low speed until just combined. Increase speed to medium; add eggs and beat for 2 minutes, scraping sides of the bowl occasionally. Gradually stir in up to 2 more cups flour, mixing until a soft dough forms.

Turn dough onto a lightly floured surface and knead until smooth and elastic, about 10 minutes. Dough will be very sticky; use a scraper and add remaining flour only as needed. Shape dough into a ball and place in a large greased bowl; turn to coat. Cover with a towel and let rise in a warm, draft-free place until doubled in volume, about 1 hour.

Punch down dough starting from the center, then pushing in the edges. Transfer onto a lightly floured surface and cut dough in half. Cover with a bowl and let rest for 15 minutes.

Meanwhile, combine remaining 1/2 cup sugar, lemon zest, and mace in a small bowl. Melt 2 tablespoons butter in a small pan. Grease a 10-inch fluted tube pan with cooking spray.

Cut each dough half into 16 pieces. Shape each piece into a ball by tucking ends under. Dip tops in melted butter and place half of balls in the tube pan; sprinkle with 1/2 of the lemon mixture. Repeat with remaining dough balls, butter, and lemon mixture. Cover with a towel; let rise in a warm place until doubled, about 45 minutes.

Preheat the oven to 350 degrees F (175 degrees C). Place tube pan on a cookie sheet.

Bake in the preheated oven until bread is golden and sounds hollow when lightly tapped, about 35 minutes. Cool in the pan for 5 minutes; remove and let cool on a wire rack.