In the food processor, turn walnut into meal. Add butter, salt, sugar, flour, baking powder, and the egg. Mix until it forms a ball. Wrap up and refrigerate for a couple of hours. Flour work surface and pastry. Use two-third of the dough. Work it out a bit to soften it up, and roll out into a 0.12''/3mm thick disk. If it gets too warm, freeze pastry for a few minutes between steps. Shape pastry into a 9''/23cm diameter tart ring. Trim off excess dough and freeze for 10 minutes. Roll out remaining pastry into a large strip; freeze to harden and cut into strips that matches the height of the ring. Keep frozen until ready to use. Make a hole in the center using a 3''/8cm tart or cake ring. Grease and wrap ring with parchment paper and place in the center of the tart shell. Gently moisturize around it with a brush and finish with the pastry strip. Prick with a fork here and there. Freeze tart shell for 30 minutes at least before baking.
Peel and wash carrots. Grate carrots and and press in paper towels to remove excess moisture. In the food processor, turn walnut into meal. Add butter, sugar, flour and the egg. Mix until smooth, and add grated carrots. If too soft, refrigerate before piping.
Blind bake tart shell for 20 minutes at 350ºF/180ºC. Add walnut carrot cream, and dot with a a third of pineapple cubes. Bake for an additional 30/35 minutes. Remove tart rings and let cool completely.
For the white chocolate ganache: Heat up heavy cream and vanilla and pour in chocolate. Mix using an immersion blender. Refrigerate ganache overnight. To finish the cream cheese Chantilly: In the stand mixer fitted with the whisk attachment, beat cream cheese until smooth. Add ganache and mix on low speed until combined. Increase mixer speed and beat to medium-firm peaks. Pipe out immediately.
Cover baby carrots (peeled) with carrot juice. Cook for 25 minutes or until fork tender. Drain and save carrot juice for the marmalade. In the food processor, turn cooked carrot into small pieces. Let cool and reserve for the final marmalade.
For the jelly, combine sugar with agar-agar, and set aside. Reduce carrot juice (600g) to a cup/250g. It should take an hour on medium heat. Whisk in sugar-agar mixture, and cook for 2 minutes on medium-low heat. Cool and refrigerate to set, or place on ice water. Once completely set, smooth carrot jelly out with an immersion blender. Take out 3oz/100g jelly and combine with 5oz/150g cooked carrot pieces; keep refrigerated. Save remaining jelly for garnishing.
Cut pineapple into dice. In a hot frying pan, sautée pineapple with brown sugar for a couple of minutes. Flambé with rum – let cook on low heat until caramelization; cool. Spread carrot marmalade on the pie, and top with cream cheese Chantilly using the St Honoré pipping pastry tip. Garnish with carrot jelly and flambéed pineapples. Decorate with mint leaves if desired. This carrot pie can be made in advance and kept frozen for up to a month. Enjoy!