Preheat oven to 350°F.
Grease and flour a 9x13 pan. (Unsweetened cocoa can replace the flour if you don't want any white areas on the outside of the brownies.).
Melt the butter in a small saucepan and add the chocolate. Remove from stove top if electric or turn off gas and let the chocolate melt from the accumulated heat in the butter. If necessary, return to low heat to finish the melt. In any case, let it all cool to room temperature.
In a food processor with metal blade, combine the whiskey and prunes. Run at high speed until finely chopped. Add the eggs. Blend well. Add sugar in 3 or 4 increments. Blend until light and thick. (This is important.).
Scrape the mixture in to a medim bowl. With a broad spatula or big spoon, fold in the melted chocolate/butter mixture. When nearly uniform in color, fold in the cup of flour and 1/4 tsp of cinnamon.
When nearly uniform in color, scrape into prepared pan.
Bake for 25 minutes at 350. Cut into 12 or more pieces after they are cooled.
Note: You can add some pecans or walnuts to the batter or the top of the brownies. Consider putting in a bit of grated fresh orange peel.