Using either an electric mixer or a large bowl and mixing-spoon:
- Beat the coconut oil and butter on medium speed until it gets nice and creamy. If you're using your hand, tip the bowl and swirl the spoon quickly to fold air into the mixture.
- Pour in your sugar.
- Beat the mixture again for about 5 minutes until it gets fluffy. Again, if you're doing this by hand, you'll need to swirl air into the mixture quickly. Your arm will be tired!
- Add the large egg.
- Add the egg yolk. To get just the yolk, break the egg in half and pour the egg yolk back and forth until the egg whites drain out of the shell.
- Add the vanilla.
- Beat again for about 2 minutes until everything is combined.
- Slowly add the dry ingredients you mixed earlier, a little at a time, while beating the mixture lightly (or at a low-speed). Again, if you're doing this by hand, then it will be a bit tiring. What I found helps is to use a large metal tablespoon to break up the dough as I mix.
- Mix in your chopped walnuts.
Using a teaspoon:
- Scoop out small portions of the dough.
- Shape into round balls about 1 inch in diameter.
- Place on a lightly greased baking tray about 2-3 inches apart.
Try to keep the balls even; otherwise, your cookies will cook unevenly.