Add the rolled oats and wheat flour into a mixing bowl. Grate the frozen butter into the bowl. Using clean hands, toss gently to combine. Snap andy large bits of butter with your fingers. Toss in the walnuts, thyme and salt. Drizzle the beaten egg over the mixture. Next toss again and press into to form the grainy Irish Oatcake Dough.
Form the dough into 12 to 14 1 inch dough balls. Give the balls a roll in the sesame seeds and place 2 inches apart on the prepared baking sheet.
Press each dough ball into a circle using the bottom of a glass.
Bake for 12 to 15 minutes or until the crackers are just golden brown and the butter is bubbly.
Remove from the oven and lets these savory oat crackers rest for 10 minutes. Move them to a baking rack to completely cool. Enjoy!