Preheat oven to 350°F. Spray a 9x9-inch baking dish with non-stick cooking spray or line with parchment paper.
Combine your ground flaxseed and water, and set aside to gel for 5 to 10 minutes to create your flax egg.
In a medium bowl, whisk together flour, baking powder, salt, baking soda, and cinnamon until combined. Whisk in fresh orange zest until orange zest is incorporated, and set aside.
In the bowl of a stand mixer, or with an electric hand mixer, add in your sugar and orange zest. Massage your orange zest into the sugar. Next, add your room temperature butter and cream together, then beat the butter and sugar for about 3 to 4 minutes. Next, add in the flax eggs and mix until creamy. Finally, add in the plant-based milk, orange juice, and vanilla. Beat until everything is incorporated.
Add dry ingredients to wet ingredients, and stir until just combined. Toss your cranberries in 1 tbsp of flour and then gently fold the cranberries into the batter. Pour batter into prepared baking dish.
Next, create the crumble. Massage the sugar and orange zest together, then add the flour, oats, cinnamon, and melted butter. Mix until it resembles a crumbly texture. If the mixture is still very dry, add either 1 tbsp of plant-based milk or orange juice. Sprinkle over the top of the batter.
Bake the cake 40 to 50 minutes, or until a toothpick inserted in the center comes out clean or with just a few crumbs. Let the cake cool completely.
While coffee cake is cooling, prepare the glaze. Stir together the sifted powdered sugar and start with 1 tbsp orange juice, and orange zest, and mix until smooth. Add additional fresh orange juice as needed to reach the desired consistency. Drizzle the glaze over the cake, and if desired, top with a sprinkle of orange zest. Allow the glaze to harden, then serve.
Storage Instructions: Store the coffee cake covered at room temperature for up to 3 days or refrigerate for up to 5 days, where it will stay moist and flavorful thanks to the juicy cranberries and citrus. To freeze wrap slices or the whole cake tightly in plastic, then foil, and freeze for up to 2 months for easy cozy winter treats whenever the craving hits