Add flour, buttermilk powder, salt, and baking powder to a stand mixer. Fit with paddle and mix on speed 1 for one minute. Chop (or puree) dates and add to flour mixture. Mix on speed 1 for one minute. Chop butter and add to flour mixture. Mix on speed 1 until dough is crumbly. Slowly add in tangerine juice. Allow to mix until mixture becomes mealy and holds its shape when pressed. (You may not need all the juice.) If dough is too dry, add a little ice water, just a teaspoon at a time, until dough mostly sticks together. A little crumbly is what you want. Knead a few times with your hands then form into a ball and refrigerate 10 min. Roll to desired shape.
Cooking Instructions
For a one crust pie (shell), roll dough out to about 1/4 inch thickness. Carefully add to greased pie plate. Flute edges and prick bottom with fork. Bake at 375 10 minutes.