In the mixer fitted with the hook attachment, combine flours, sugar, salt and yeast. Add eggs and milk and mix on low speed – increase to medium for about 10 min and mix until smooth; scraping down the sides of the bowl and hook as you go. Add cubed butter gradually and continue mixing until completely smooth and elastic; it should take 10 to 12 min. The dough should not stick to the touch. Let rise for 90 min or until it has doubled in size. Transfer onto a clean (no flour still) work surface, deflate and fold into a flat slab. Store on baking tray lined with silicon mat and wrap up, and freeze for an hour. This will put the brioche to ‘sleep’ – then place in the refrigerator overnight. Though, at this juncture the brioche can be stored in the freezer for up to 2 week.
In a narrow and tall cup, put all ingredients in order and blend well using an immersion blender or Vitamix. Chill for at least an hour or best overnight. Resting the batter allows the flour to fully absorb the liquid and gives the gluten a chance to relax making the most delicate, melt-in-your-mouth crepes. Shake crepe batter before using. Heat up a crepe pan, grease lightly with frying oil and coat bottom of pan, when edges get brown, run a spatula around the crepe and flip. Reheat and grease pan between each crepe. Yield ≈8 crepes.
Peel and clean rhubarb. Trim off ends and divide in large stiks (if rhubarb stalks are too thick, split in half lengthwise). Arrange rhubarb, orange juice and sugar in a saucepan. Bring to boil and cook simmer for 2 min. Turn the heat off, put a lid on and leave rhubarb alone to poach. When at room temp, check the doneness. The rhubarb stalks should remain whole and just tender.
Peel and make apple cylinders using a corer. Soak apples in water and lemon juice until ready to use. Drain apples. In a hot frying pan, brown apples with butter and sugar for about 8 min, add cinnamon. Transfer onto a plate to cool and save remaining juice left in the pan for the bananas.
Peel, divide in 2 and split in half lengthwise. Reheat pan that was used to cook the apples, throw in bananas, add more sugar and butter if needed and sautee on high heat for about 90 sec on each side. Transfer onto a plate to cool.
Lay a couple of plastic wrap sheets on the countertop. Overlap 4 crepes first and arrange bananas, rhubarb, apples, jam – repeat this step once. Fold into a 9.5 inch (24cm) log and freeze for 2 hours max. On a floured work surface, roll out two-third of the chilled brioche 1.5 lb/650g into a 13''x13''/33x33cm ≈1/4''/5mm thick sheet. Place over a large tray and refrigerate to rest.
When ready, place brioche over a floured work surface and reajust its size. Remove excess flour and egg wash brioche sheet. Unwrap and place the winter fruits log in the center and wrap. Egg wash seams, seal and flatten corners with the rolling pin – egg wash and wrap sides tight around log. Flip wellington, egg wash and refrigerate for an hour or for up to 2 days (do not freeze). Egg wash again and score. Make a few small holes on the top using a bamboo skewer.
Leave coulibiac to proof at room temperature 75ºF/24ºC for about 90 minutes.
Bake coulibiac at 350ºF/180ºC for 35 minutes. Glaze with simple syrup if desired. Let cool for 4 hours prior serving. Can be refrigerated for up 4 days. Serve at room temperature or slightly warm. Enjoy!