Mix together brown sugar and heavy whipping cream in a large microwave-safe bowl (at least two quarts). The bowl should be deep enough to allow the mixture to boil, without boiling over.

Microwave mixture on high for 5 minutes, remove from microwave, and stir.

Add pecans and return to microwave for 4 minutes on high.

Remove from microwave, add butter and stir until mixture loses gloss and begins to thicken (about 2 minutes). The mixture should be thickened and beginning to form along the sides of the bowl.  If the caramel is still runny, cook it a bit longer.  Microwave in additional 1-minute increments.

Turn out on a greased marble slab or parchment paper. Wax paper will melt.

Makes approximately 2 dozen pralines. Allow to cool thoroughly.