Preheat the oven to 375°F (190°C) and line a round 9" (23 cm) cake pan or cast iron skillet with parchment paper.
In a small bowl, whisk together the milk and lemon juice and set aside for 10-15 minutes, until curdled.
In a large mixing bowl, mix together the flour, sugar, baking soda and salt. Chop the butter into small pieces and add to the flour mixture. Use a pastry cutter, fork, or your hands to incorporate the butter into the flour mixture.
Stir in the milk mixture. Once the dough comes together, stir in the raisins, if using, and place it on a floured surface and knead it until you have a smooth dough, adding flour as needed so that it's not too sticky to handle.
Form the dough into a ball and place onto the pan. Using a knife, cut an "X" into the top of the dough.
In a small bowl, stir together the milk and melted butter for topping. Brush the mixture overtop of the dough, saving the extra mixture for later.
Bake for 50-55 minutes, basting the dough every 10 minutes with the milk mixture (do this quickly to ensure the dough isn't out of the oven for long). Once done, the outside should be golden-brown and the center shouldn't be doughy.
Allow the bread to cool for at least 10 minutes, then transfer to a cutting board. Slice and serve!