4-5large heirloom or garden tomatoes sliced ½ to ¾ inch thick
2tablespoongrated or pearled parmesan
pinch flaky sea salt (optional)
Mix the mayo, mustard, garlic, herbs, salt & pepper. Stir to combine. Set aside.
On a lightly floured counter, roll out the pastry to fit an 8.5 x 12-inch baking tray (these are similar to 9x13 cake pans but slightly smaller and with edges that are about an inch high. Set aside and don't line the tray yet.
Slice the tomatoes.
If you like, do a 'dry-fit' with your tomatoes. Place a piece of parchment or paper towels on the baking tray and arrange your tomatoes in the design that you like, fitting as many in as you can but not overlapping them or packing them too close together. Slide the parchment out of the tray, being careful to keep your design basically in place.
Lay the puff pastry into the tray and dock the bottom with a fork.
Spread the herb mixture evenly over the docked pastry, then sprinkle with some of the grated parmesan.
Lay in the tomatoes and sprinkle on a bit more parmesan.
Brush the beaten egg on the sides of the pastry so it will bake up a golden brown.
Bake in a 400f pre-heated oven for about 30 minutes or until pastry is puffed and the tomatoes are looking cooked through but not soggy. Cover the edges with foil if needed to prevent over-browning.
Cool, sprinkle with flaky sea salt and slice. Enjoy!