Start with preheating the oven at 350-degrees F.
In a large mixing bowl, toss together cubed white bread slices and the raisins.
In a saucepan, mix milk and sugar.
Place the saucepan over the stove at low to medium heat. Let it simmer until the sugar is dissolved.
Remove the saucepan from heat and add butter into it. Mix until the butter is dissolved.
Pour the milk mixture over the bread and sit for 8 to 10 minutes.
Mix condensed milk, evaporated milk, eggs, nutmeg, cinnamon, and vanilla in a separate bowl.
Pour egg mixture over the bread and gently toss it.
Pour the entire mixture into a 9 by 11 casserole dish.
Cut the 3 tbsp of butter into small pieces. Spread them over the pudding.
Bake the pudding for 35 to 45 minutes or until the top is golden and crusty.