Preheat the Oven: Preheat the oven to 375–400°F (190–200°C). Choose a medium-sized casserole or baking dish that can hold the rice mixture.
Beat the Eggs: Crack 4–5 large eggs into a mixing bowl and beat with a whisk or fork until the yolks and whites are fully combined.
Mix in the Sugar: Add ¾ cup of granulated sugar to the beaten eggs and whisk until well combined.
Add the Milk: Pour in 2 cups of milk and whisk until the mixture is smooth.
Stir in the Cooked Rice: Add 2 cups of cooked rice, preferably leftover rice, and stir gently until the rice is evenly distributed throughout the custard.
Add the Vanilla Extract: Pour in 1 teaspoon of vanilla extract and stir to combine.
Fold in the Raisins: Add ½–1 cup of dark or golden raisins and stir gently to distribute them throughout the mixture.
Add the Butter: Pour the rice mixture into the casserole dish and scatter 1–2 tablespoons of butter, cut into small pats, over the top.
Bake the Rice Pudding: Place the dish in the preheated oven and bake for approximately 30–35 minutes, until the edges are set and the center still has a slight jiggle.
Check the Custard: Check that the pudding is mostly set but remains soft in the center. For food safety, use a food thermometer to confirm that the egg mixture reaches 160°F (71°C).
Let the Pudding Rest: Remove the dish from the oven and let the pudding rest for several minutes. The custard will continue to set as it cools.
Serve the Rice Pudding: Spoon the warm pudding into serving bowls while it is still creamy. Refrigerate any leftovers within two hours.