Warm the milk. Heat 3/4 cup of milk until warm to the touch, about 105–110°F. It should feel like a warm bath—not hot, or it can kill the yeast.

Activate or mix the yeast. If using active dry yeast, sprinkle 2 1/4 teaspoons over the warm milk with 1 teaspoon sugar and let it foam for 5–10 minutes. If using instant yeast, just add it to the dry ingredients in the next step and continue.

Combine dry ingredients. In a large bowl, whisk 3 cups flour, 1/4 cup granulated sugar, and 1 teaspoon salt. This sets a balanced base and prevents clumps.

Add wet ingredients. Stir in the milk-yeast mixture (or warm milk if using instant yeast), 1 large egg, 4 tablespoons melted butter (slightly cooled), and 1 teaspoon vanilla extract. Mix until a shaggy dough forms.

Knead until smooth. Knead by hand on a lightly floured surface for 8–10 minutes, or with a dough hook for 6–8 minutes. The dough should be soft, smooth, and slightly tacky but not sticky. If it’s very sticky, add a tablespoon of flour at a time. Don’t over-flour—soft dough bakes tender bread.

First rise. Place the dough in a lightly oiled bowl, cover, and let rise in a warm spot until doubled, about 60–90 minutes. It should look puffy and spring back slowly when poked.

Make the cinnamon filling. In a small bowl, mix 1/2 cup light brown sugar, 2 teaspoons ground cinnamon, and a pinch of salt. Melt 2 tablespoons butter for brushing the dough later.

Roll out the dough. Punch down the dough and roll it into a rectangle about 9x16 inches. Keep the edges even so the swirl is tidy.

Add the swirl. Brush the dough lightly with melted butter. Sprinkle the cinnamon-sugar mixture evenly, leaving a 1/2-inch border along one short edge to help the seam seal.

Roll and seal. Starting from the short edge opposite the border, roll the dough up tightly like a jelly roll. Pinch the seam closed and tuck the ends under so sugar doesn’t escape while baking.

Second rise. Place the log seam-side down in a greased 9x5-inch loaf pan. Cover and let rise until the dough crowns about 1 inch over the rim, 45–60 minutes. Preheat the oven to 350°F.

Bake. Bake for 30–38 minutes, until the top is deep golden and the internal temperature reaches about 190–195°F. If the top browns too quickly, tent with foil for the last 10 minutes.

Cool and (optional) glaze. Let the loaf cool in the pan for 10 minutes, then transfer to a rack. For a light glaze, whisk 1/2 cup powdered sugar with 1–2 tablespoons milk and drizzle over the warm loaf. Cool at least 45 minutes before slicing so the swirl sets.