Preheat your oven to 350°F. Sift together flour, baking soda, baking powder and salt. Set it aside.
Using a hand mixer, cream together butter and sugar on medium speed. When it looks whipped, add egg and vanilla and whip again until the mixture looks light and fluffy.
Add the flour mix and whisk till the batter looks fluffy.
Add all the mix-ins, including chopped nuts and dried fruit and using a spatula, fold everything in till incorporated.
Using a cookie spoon, scoop and drop the dough on a parchment or aluminum lined baking sheet, leaving a 1½-2 inch gap between cookies. Wet your fingers and gently press down on the cookies to flatten them a little.
Bake in the preheated oven for 13-14 minutes on the center rack, until golden at the bottom and edges.
Wait for 2 minutes after which transfer the cookies to a wire rack for cooling.
Melt the butter and bring the egg to room temperature. The key to a soft, chewy oatmeal cookie is melted butter. Rather than creaming to create structure, the butter provides moisture and flavor and ultimately will make the cookie chewy. Just make sure to cool slightly before mixing. A room temperature egg ensures better emulsification. To speed up the process, add the egg to a bowl of warm water for a few minutes before mixing.
Add more brown sugar for cookie sweetness. The sweetness in these cookies is more like a snack bar. Add an additional 2-4 Tablespoons brown sugar (light or dark) for a sweet cookie recipe.
Use a small cookie or ice cream scoop to portion out the cookies. This makes it easier to ensure you are forming cookies all roughly the same size.
Bake to desired tenderness. My girls baked them for 13 minutes, which made for well-done cookies where the edges were set, but the centers were slightly chewy. For super soft oatmeal cookies, bake for 10-12 minutes.
Allow the cookies to cool on the baking sheet. The oatmeal cookies will be very soft as soon as they come out of the oven. Make sure to let cool for at least 2 minutes on the baking sheet to allow them to set.
Bake some now and save the rest for later. The unbaked cookie dough will keep in an airtight container in the fridge for up to 5 days.
To freeze cookie dough, scoop the cookie dough and place on a parchment-lined baking sheet, flattening as directed. Transfer to the freezer for 1 hour, or until each individual cookie dough ball is frozen. Transfer to a plastic freezer storage bag, seal tight, label, date and freeze for up to 3 months. No need to thaw before baking, simply add an additional 2-3 minutes to the baking time.
To freeze baked cookies, cool completely and transfer to a plastic freezer storage bag, seal tight, label, date and freeze for up to 6 months. Reheat in the toaster oven or microwave when ready to enjoy!
Note: The nutrition facts below are my estimates for one cookie based on 36 servings. If you are following any diet plan, I recommend cross-checking with your preferred nutrition calculator.