Supreme the orange, removing all the pith. Add all pieces of orange into the food processor.
Pulse or process for 5 – 10 seconds, should remain chunky
Pour the mixture into a medium saucepan and add sugar and water.
Stir and cook on medium-high and bring to a boil. Cook, stirring occasionally, for 5 minutes. (be careful not to let it bubble over)
Take off the heat and use a stick blender and process until smooth. (or, wait until it cools and then return it to the food processor and process until smooth)
Let it cool to room temperature.
Using an ice cube tray, fill each cube halfway. Freeze. (at least one hour) Leave these in the freezer until ready to add to the cake batter.
Save the rest of the jam for serving, refrigerate until ready to use.
Preheat oven to 350°.
Grease/spray and flour a 15 cup Bundt cake pan. Spray or grease, and dust lightly with flour and lightly tap out the excess. (or use my suggestion for cake goop!) Try not to get too much oil/flour in the design of the pan. If it looks thick/crusty/uneven, that’s what the final cake will look like when turned out.
Make sure all ingredients are the same temperature. Leave the butter, eggs, and buttermilk out on the counter until they are completely room temperature to ensure emulsification. The ingredients will not ‘go bad’. VERY IMPORTANT they’re the same temp. (I leave mine out for 4 hours, just fyi)
In a small bowl or 2 cup measuring pitcher, crack open and add all eggs. Set aside.
In a medium bowl, sift together the dry ingredients. (Flour, baking powder, baking soda, salt) Set aside.
Into a small bowl or 2 cup measuring pitcher, measure out the buttermilk, orange juice and vanilla. Set aside.
In the bowl of a stand mixer fitted with a paddle attachment, cream together the butter and sugar until light and fluffy (about 5 minutes).
Lift the mixer head, remove the paddle and set it inside the bowl.
Zest the 3 large oranges into the bowl. Replace the paddle.
Mix until zest is well blended.
While the mixer is on low, add the eggs, one at a time until well mixed.
Keeping the mixer on low, add the flour mixture into the large bowl, in 3 parts, alternating with the buttermilk mixture. Starting with the dry and ending with the dry. Do not over mix, stir only enough after each addition to get all the ingredients wet. There should not be any lumps. If there are, do not try and mix them OUT, less mixing is better.
Carefully fill the prepared Bundt pan with half of the batter.
Pop or remove the frozen cubes of cranberry jam out of the tray and arrange the cubes in a ring in the middle of the batter. (not touching any edges, keep them in the middle!)
Carefully add the remaining batter from the large bowl into the Bundt pan, covering the jam cubes.
Place into pre-heated oven, in the middle of the oven, in the middle of the rack.
Bake for 50 minutes, then cover with foil. Bake for an additional 10 minutes or until a skewer inserted near the center comes out clean. (avoid the jam)
*the baking time could vary, it might take longer, try not to over bake. It should be golden brown. If using a dark, non-stick pan, it might take less time.
Remove from oven, and do not invert, place on wire rack to cool completely in the pan.
Once it’s cooled to room temperature, invert upside down onto a serving plate and tap firmly. It should immediately drop out of the pan if it’s been sprayed/floured correctly.
While it’s cooling, mix the powdered sugar and orange juice to create a simple glaze.
Once the cake is completely cooled, carefully pour the glaze on the top.