heat oven to 350. (375 for a metal pan.) butter a 9 x 13 baking pan.

in a microwave- or oven-safe mixing bowl, melt together 1-1/2 sticks butter and 4 squares unsweetened chocolate (melt til all butter is melted and the chocolate is starting- then stir together til the heat melts the chocolate).  dump in 2 cups sugar (this also serves to cool it down some) and stir til blended.  stir in 3 big eggs (this is what makes it chewy) til well-blended.  stir in 1 teaspoon vanilla. stir in 1 cup (lightly lightly spooned into cup) flour and stir til well-blended.  scrape into the prepared pan and bake 30-35 minutes - don't overbake! - til a toothpick stuck in center comes out with Fudgy Crumbs.  cool completely before cutting (right).

of course you can put in chocolate chips or melt york peppermint patties on top or whatever.