In a bowl, cream butter with the sugar and the brown sugar. Add the flax seeds.
In another bowl, beat eggs and vanilla. Add the flax seed mix and stir.
Sift the flour and the baking soda. Incorporate the oat flakes and add to the first mix.
Shape the dough into rolls of about 4 cm (1½ inch) of diameter. Place in the freezer for about an hour.
Preheat the oven at 350°F (175°C).
Cut the rolls of dough into slices of 0.5 cm (1¼ inch) thick.
Place on a greased cookie sheet. Cook for about 12-15 minutes until the edges of the cookies are golden.