Prepare a large tube pan; line the bottom with brown paper and grease the pan and lining. Preheat oven to 140ºC . Cut butter and sugar together until it resembles cornmeal. Cover the pecans and dates with the flour (in large bowl); rub together so all pieces are well-floured. Dump sugar and butter on top; mix. Break in whole eggs (fewest possible) until you have the a wet mass, but not a batter. Add vanilla extract, and pour into prepared cake pan. Bake until done, 1 1.5 hours.