Place a rack in the center of the oven and preheat oven to 350℉. Grease a 9×5-inch metal loaf pan and line it with a strip of parchment paper.
In a large bowl, whisk together oat flour sugar, baking powder, baking soda, and salt. Add chunks of butter and work the butter into the flour with your fingers.
Stir in the eggs, orange juice, and orange zest and gently mix together to incorporate. Fold in the cranberries.
Place in the oven and bake until the cake is golden brown and set, about 70-75 minutes. The edges should start slightly coming away from the sides of the pan and a tester inserted in the center should come out clean.
Remove from the oven and allow to cool in the pan for 30 minutes, then turn out onto a wire rack to cool completely.