Cream the butter and sugar; beat in egg. Combine flour, baking powder, salt and soda. Add dry ingredients to creamed mixture alternately with orange juice. Blend until smooth. Add dates and nuts. Pour batter into a greased/floured 2 pound coffee can. Place on a trivet in the crockery pot. I used a canning jar lid. Cover can with 4 to 5 paper towels. Place crock pot lid on resting against a couple of toothpicks or a prop on one side so the steam can escape. Cook on high setting 300ºF. and allow 3 1/2 hours for a 3.5 quart crock pot or 4 hours for the larger 4 1/2 quart crock pot, till the toothpick inserted into the center comes out clean. Cool on a wire rack for 10 minutes. Remove from can and cool.