Mix together flour and pecan meal; add melted margarine. A food processor works great for this. Using your hands, pat down mixture down in a 9 X 13 " glass dish and bake at 350 degrees F for 20 minutes. Bring out of oven and let cool.
On top of crust, spread 3 cups mashed strawberries. Then, mix cream cheese (at room temperature) and powdered sugar until blended, then add Cool Whip and mix. Lastly, add remaining 1 cup mashed strawberries to mixture. Spread evenly on top of strawberries in casserole dish and freeze.
Let thaw for 20 - 30 minutes, cut into squares, and serve.