Chocolate chip date nut cake

One very long time favorite from Ivanhoe, Minnesota.
1 cup boiling water
1 cup cut up dates
1 tsp soda
1 cup butter (200 grams)
1 cup sugar
2 eggs
2 TBSP cocoa
2 cups flour
1 tsp vanilla
1 bar bittersweet chocolate
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Add water to dates and soda. let sit. heat oven to 350 deg.
Beat butter and sugar and add eggs. Add cocoa and flour and remaining ingredients except for chocolate which put on top of batter in buttered and floured 13x9" pan. bake about half and hour until done.