Thaw the pastry for 30 minutes. Preheat the oven to 400 degrees.
Thaw the spinach. Squeeze by handfuls to remove excess water. Combine the spinach, cheese, leek, and garlic in a bowl and set aside.
Unfold the pastry onto a flat surface and brush with soymilk. Top the entire surface with the spinach mixture and, beginning on a long side, roll up jelly-roll style.
Cut crosswise onto 18 slices. Brush with soymilk and place on parchment-lined cookie sheet. Bake for 15 minutes or until golden brown