Begin by zesting and juicing the orange, setting the zest aside for later use. Soak the dried cranberries in orange juice for about 10 minutes to enhance their flavor. After soaking, strain the cranberries and pat them dry with a paper towel.

In a skillet over medium heat, roast the pistachios for 3-5 minutes until fragrant. Stir frequently to prevent burning. Once toasted, let them cool slightly, then roughly chop them. Add to a mixing bowl with rolled oats and dried cranberries.

Sift together all-purpose flour, baking powder, baking soda, cinnamon, and salt in a separate bowl. Set aside.

In a large mixing bowl, cream together the softened unsalted butter and light brown sugar using an electric mixer for about 2-3 minutes until fluffy. Incorporate the orange zest.

Add the large egg and vanilla extract to the butter and sugar mixture. Beat until thoroughly combined, about 1-2 minutes.

Gradually add the dry ingredients to the wet mixture, mixing on low speed just until incorporated. Fold in the oat, pistachio, and cranberry mixture using a spatula.

Scoop the cookie dough in heaping tablespoons onto a parchment-lined baking sheet. Cover with plastic wrap and refrigerate for at least 30 minutes.

Preheat the oven to 350°F (175°C).

Once the dough is chilled, place cookie dough rounds on a baking sheet, leaving about 2 inches of space between each. Bake for 14-15 minutes, rotating halfway through.

Allow cookies to cool on the baking sheet for 5-10 minutes. Then, transfer to a wire rack to cool completely.