I’ve been searching for the perfect oatmeal raisin cookie recipe but every one I tried was either too flat or too cakey. I wanted a really chewy cookie. After trying probably four recipes I started thinking of my tried and true favorite chewy chocolate chip cookie and thinking about how perfectly chewy it was because of the melted butter in the dough. So I started with the base of that dough and after several adjustments on raisins, cinnamon, and oatmeal I came up with this. This is a keeper!
*After reading some comments that some people are getting puffy cookies I experimented and you definitely need to make sure that you are not adding too much flour. Please see the note in the recipe.
Preheat the oven to 325 degrees. Line cookie sheets with parchment paper. Your cookies turn out so much better with parchment paper. Believe me! Buy some!
Melt butter and let cool slightly.
Mix flour, baking soda and salt; set aside. (See Note on the proper way to measure flour)
In a medium bowl, cream together the melted butter, brown sugar and white sugar until well blended. Beat in the cinnamon, vanilla, egg, and egg yolk for 2-3 minutes until light and creamy. Mix in the flour mixture until just blended. Add the oats, nuts, and raisins. Mix until just blended.
Place 1/4 cup balls of dough onto parchment lined cookie sheet and bake for 14-16 minutes. Do not overbake. Remember I'm at sea level so if you aren't you may need longer. The edges should look brown and the centers still slightly soft. Let the cookies rest on the cookie sheet for a couple of minutes before transferring to a cooling rack.
Source: The Girl Who Ate Everything
Make sure when you measure your flour that you do NOT pack it into the measuring cups. The proper way is to spoon the flour into your measuring cup. This can make the difference between a fluffy and chewy cookie.