In a large bowl, whisk together the warm milk, brown sugar, and yeast. Let sit for 5 minutes, until foamy.
Whisk in the melted butter, eggs, flour, and salt until a shaggy dough forms. Stir in the raisins.
Turn the dough out onto a lightly floured surface and knead for 5-7 minutes, until smooth and elastic.
Place the dough in a lightly oiled bowl, cover with plastic wrap, and let rise in a warm place for 1 hour, until doubled in size.
While the dough is rising, make the cinnamon filling. In a small bowl, whisk together the brown sugar and cinnamon.
On a lightly floured surface, roll out the dough into a rectangle about 12x18 inches.
Spread the melted butter evenly over the dough, then sprinkle with the cinnamon filling.
Starting from one long side, roll up the dough into a tight log. Pinch the ends to seal.
Place the log seam-side down in a greased 9x5-inch loaf pan. Cover with plastic wrap and let rise for another 30 minutes, until doubled in size.
Preheat the oven to 375°F (190°C).
Bake for 30-35 minutes, until golden brown.
Let cool in the pan for 10 minutes before transferring to a wire rack to cool completely.