Step 1: In a mixing bowl, combine warm water, warm milk, sugar, and yeast. Let sit for 5 minutes until frothy. In another bowl, whisk melted butter, sugar, eggs, vanilla extract, and ground cinnamon.

Step 2: Incorporate flour and salt into the wet mixture, stirring until a sticky dough forms. Knead on a floured surface for 8-10 minutes until smooth and elastic.

Step 3: Place the dough in a greased bowl, cover, and let rise in a warm area for 45-60 minutes until doubled. Punch down and divide into four parts. Shape and place a boiled egg in each piece.

Step 4: Preheat oven to 350°F (175°C). After shaping, let rise for an additional 20 minutes. Bake for about 25-30 minutes until golden brown and hollow-sounding.