PUFF PASTRY

1. To make the butter block, combine the butter and bread flour  and mix until well combined. On a 13" x 18" piece of parchment paper, spread the butter into a 6" x 9" rectangle that is approximately ½" thick, using an offset spatula to square off the edges. Fold the remaining parchment paper down, using a bench scraper to square off the edges again (very square butter is very helpful!). Place in the fridge for 20-30 minutes, until it is between 60˚f and 70˚f (15˚c to 20˚c). 
2. In the bowl of a stand mixer fitted with the dough hook, combine the bread flour, all-purpose flour, and salt. Add the butter and vanilla, and mix on low until the butter is fully incorporated into the mixture. Add the water, and mix until a dough forms, 5-6 minutes. Increase the speed, and mix on high for 2-3 minutes until smooth.
3. Turn out onto a piece of plastic wrap, and pat into a rectangle with your hands. Wrap in the plastic and rest in the refrigerator for 40-50 minutes. 
4. Once it has reached the ideal temperature, bring both the butter block and the dough out of the fridge. Line a baking sheet with parchment paper. On a lightly floured surface, roll the dough out to a rectangle approximately 12" x 10". Place the butter block on the bottom half of the dough (you should have about half an inch space around the edges), and fold over the dough to 'lock' in the butter, pressing down the edges to seal it in. Tuck any excess underneath. Wrap in plastic wrap, place on the baking sheet, and rest in the fridge for 20-30 minutes. 
5. Remove the dough from the fridge. You are now going to begin the folding process. You will do a four fold, a three fold, a four fold, and another three fold.

Turn #1: 4-fold

On a lightly floured surface, roll the dough out to a 13" x 18" rectangle, using a bench scraper to keep the edges tightly squared off. Turn the dough so a long edge is facing you. Take the left edge of the dough, and fold ¾ of the way across the dough, lining up the edges. Fold the right edge to meet the left, about ¼ of the way across. Fold the dough in half, left side over right. Transfer to the baking sheet, brush off extra flour, and cover with plastic wrap. Rest for another 30 minutes.

Turn #2: 3-fold

Remove the dough from the fridge. On a lightly floured surface, repeat the rolling process - roll to 13" x 19", and square the edges. Turn so a long edge is facing you. Fold the left side of the dough ⅓ of the way across, then fold the right side of the dough over the left (so you have 3 layers of dough). Place on the baking sheet, brush off flour, cover and refrigerate. Rest for 30 minutes.

Turn #3: 4-fold

Repeat the process for a 4-fold as explained above, taking care to square the edges. Cover and rest for 30 minutes.

Turn #4: 3-fold

This is your final fold. Roll out, square off, and repeat the instructions for a 3-fold above. Cover, and rest for 30 minutes. 

Divide the pastry in half. Wrap each half tightly in plastic wrap and store in the fridge until ready to use. You will only use one of the pieces for this recipe - store the other piece, tightly wrapped, in the freezer or fridge for another project.

FILLINGS

1. To make the roasted red peppers, preheat the oven to 400˚f / 200˚c. Line a quarter baking sheet with tin foil. Place the peppers, whole, on the baking sheet and lightly drizzle with oil. Bake for 45 minutes, or until the skin is starting to darken and lift away from the flesh. Remove from the oven and allow to cool completely on the baking sheet before peeling the peppers and removing the skin and stalk. Divide the flesh from each pepper into 3 or 4 pieces, and cut into strips. Place into an airtight container until ready to use. 
2. To make the mushrooms, heat a skillet or frying pan over medium heat. Add a good drizzle of olive oil, then add the onions and garlic, and cook for one minute, stirring frequently. Season with salt and pepper. Add the mushrooms and thyme, and cook for 15-20 minutes, stirring frequently and adding more oil if needed, until the mushrooms are cooked and beginning to go golden brown. Season well. Remove from the heat and set aside until ready to use - store in an airtight container in the fridge if preparing ahead. 

ASSEMBLY

1. Line a baking sheet with parchment paper. On a lightly floured surface, roll out your puff pastry to a rectangle 5mm (¼") in thickness. If you are using pre rolled store bought pastry, lightly roll to remove any creases. Using a pastry cutter or very sharp knife, cut rectangles 8cm x 12cm (3" x 5"), and transfer to the baking sheet, leaving a little space between each. You should get approximately 12 rectangles. Transfer the baking sheet to the fridge for at least 30 minutes. 
2. Preheat the oven to 400˚f / 180˚c. Using a sharp knife, score a rectangle 1cm in from the edge of the pastry, taking care not to cut right through. Repeat with the remaining rectangles of pastry. 
3. Spread about 1 tsp (or a little less if you do not want them too spicy) of Hot Chili pesto on each tart, keeping inside the scored border. Top with 1 Tbsp of the mushroom mixture, and a few of the strips of roasted red pepper. Brush the outer exposed edge of pastry with egg wash. 
4. Bake the tarts for 15-18 minutes, until the pastry is puffy and golden brown. While the tarts are baking, fry the halloumi in a skillet or frying pan over medium heat, until golden brown on both sides. Cut into cubes. 
5. Once the tarts are baked, remove from the oven, and top each with a few cubes of halloumi. Garnish with a sprig of thyme if desired. Serve warm. 
6. Store leftovers in an airtight container. Best eaten on the day that they are made.