In a large mixing bowl, whisk together the flour, sugar, salt, and instant yeast until well combined.
In a separate bowl, whisk together the warm milk, melted butter, egg, and vanilla extract until smooth.
Pour the wet ingredients into the dry ingredients and stir with a wooden spoon or spatula until a sticky dough forms and all flour is incorporated.
Cover the bowl tightly with plastic wrap or a clean kitchen towel and let the dough rise at room temperature for 8 hours or overnight, until doubled in size and bubbly.
After the dough has risen, lightly flour a clean surface and gently turn the dough out onto it. Shape the dough into a rough loaf by folding it over itself a few times, but do not knead.
Place the dough seam side down into a greased 9×5-inch loaf pan. Cover loosely with plastic wrap and let it rise for 45 minutes to 1 hour, until puffy and nearly doubled.
Preheat the oven to 350°F (175°C).
Bake the bread in the preheated oven for 35 to 40 minutes, until the top is golden brown and a toothpick inserted into the center comes out clean.
Remove the bread from the oven and let it cool in the pan for 10 minutes, then transfer it to a wire rack to cool completely before slicing.