What I actually do for chocolate rice pudding:

1 C rice
1 C milk
scant 1/4 C sugar
1 tbsp cocoa
~ 1 tsp butter (or less)

Cook as below.  I forgot the vanilla and cinnamon.  It was still delicious.

Another experiment was Pumpkin Rice Pudding:

I substituted half the milk for pumpkin directly, but it was kind of
too dry.  I should have held back a little rice, or added a little
milk.  It was a four-cups-rice recipe, and I used my pumpkin squares
spice mix:

1.5 tsp cinnamon
3/4 tsp ginger
1/2 tsp nutmeg
1/4 tsp allspice
1/4 tsp cloves


Original text:

Based on http://www.suite101.com/content/quick-chocolate-and-classic-rice-pudding-recipes-a315727:

    * 3 cups (1 lb / 454 g) of cooked rice
    * 3 cups (24 oz / 720 ml) of milk
    * 2/3 cup (5½ oz / 150 g) of sugar
    * 2 tablespoons (1 oz / 30 g) of butter
    * 1/2 cup (3 oz / 90 g) of raisins
    * 1 tsp (5 ml) of vanilla extract
    * 1 tsp (5 ml) of lemon juice
    * 1 tsp (5 g) of cinnamon

   1. Combine the rice, milk, sugar, butter and raisins and cook on a Medium heat for 25 minutes, stirring occasionally, until most of the liquid is absorbed.
   2. Stir in the vanilla extract, lemon juice and half the cinnamon.
   3. Spoon into serving dishes and sprinkle with the remaining cinnamon.

Chocolate Rice Pudding

To make chocolate rice pudding, take any of these recipes, blend 3
tbsp of cocoa into the milk and add 1 tbsp of butter to the original
quantity. Stir in some chocolate morsels just before serving.