Preheat oven to 350 degrees Fahrenheit.
In the bowl of an electric mixer, cream together sugar and butter until fluffy. Add eggs and vanilla and mix until incorporated, scraping down the sides as needed.
In a separate bowl, stir together flour, baking powder and salt. Add the flour mixture, boiling water and buttermilk to the wet mixture alternately, starting with HALF of the flour mixture, then half of the buttermilk, half of the boiling water, etc., mixing in between, until all are incorporated. Quickly mix in chopped pecans.
Spoon mixture into Silpat mini fluted cake pan (that you've placed inside a half-sized baking pan), ensuring each cup is no more than 3/4 full. Bake for approximately 17-19 minutes, or just until a toothpick inserted into the center comes out clean.
Let cool in the baking mold for 10-15 minutes, then carefully remove the cakes.
Make the caramel pecan drizzle by stirring together brown sugar, butter, and heavy cream or half and half in a sauce pan. Place it on the stove top over medium-high heat and stir constantly while allowing it to come to a boil. Remove it from heat and stir in vanilla and 1/2 c. chopped pecans. Drizzle over warm cakes and serve immediately. Cakes and drizzle are best when served warm. Quickly warm them in the microwave if they've cooled.