Preheat oven to 350°F (175°C).
In a large bowl, cream together the butter and brown sugar.
Add eggs and vanilla, and mix well.
In a separate bowl, combine the flour, baking soda, brewer's yeast, and flaxseed meal.
Gradually add the dry ingredients to the wet ingredients, mixing well.
Stir in the oats and chocolate chips.
Drop spoonfuls of dough onto a baking sheet.
Bake for 10-12 minutes, or until edges are golden brown.
Allow cookies to cool on the baking sheet for a few minutes before transferring to a wire rack to cool completely.