Place the oat flour, pecan pieces, and cinnamon in a food processor, and process until the texture resembles coarse flour.

Add the dates, and process for about 1 minute, or until the mixture just begins to clump together. Add the milk and process until the mixture starts to ball up into dough (this will happen quickly).

Form the dough into one big ball and place it on a large piece of parchment paper on top of a cutting board or other flat surface. Press the ball flat with your hands and then place another large piece of parchment paper over the top.

Preheat the oven to 375°F. Set aside an 8-inch pie pan.

Use a rolling pin to roll out the dough into a circle that is about ⅛ inch thick. The circle should be slightly larger than the upper edge o the pie pan. (If your circle is irregularly shaped, just cut a piece of dough from another area and press it in.)

Peel off the top piece of parchment paper and carefully invert the rolled-out crust onto the pie pan. Peel away the remaining piece of parchment paper. Gently ease the crust into the contours of the pan and lightly press into place.

Use hanging crust to form the edge crust of the pie shell. Build it up some around the top edge of the pie plate so that the crust is more substantial. This will allow it to withstand the heat and resist burning when baked. 

Trim away any hanging crust (don't wrap the crust over the edge of the pan since this will make it harder to cut after it's baked). You do not need to poke the crust with a knife.

Place a piece of aluminum foil over the entire crust, loosely tucking under the corners. Place on a baking sheet and bake for 10 minutes, or until the edges are very lightly browned.