For the praline paste, lightly grease a rimmed baking sheet (a half-size baking sheet will do, but a quarter-size is better), then set it aside. Water, sugar, corn syrup, hazelnuts, almonds, and salt should all be combined in a 2-quart saucier or saucepan made of stainless steel. Cook mixture for about 10 minutes, stirring regularly with a heat-resistant spatula to prevent scorching and ensuring sugar dissolves, or until mixture turns a tawny brown and a clip-on digital thermometer reads 320°F (160°C).
When the candy has reached the desired consistency of foaminess, remove it from the heat and whisk in the baking soda right away. Next, pour the candy onto the prepared baking sheet. After roughly 30 minutes of cooling to room temperature, immediately move on to the next stage (if praline is allowed to sit out for an extended period of time after cooling, it will turn tacky and soft).
Praline should be broken up and placed in the food processor's bowl. Pulse the candy several times to break it up, then let the food processor run continuously for about three minutes, or until the praline becomes a thick paste like peanut butter. Paste should be poured into a small basin, covered, and left alone.
For the Choux, set the oven rack in the center and heat the oven to 375°F (190°C). On a piece of parchment paper measuring 12 by 18 inches, draw an 8-inch circle in the center with a pen or pencil. Put the parchment in a baking sheet with a rim so that the drawn ring is on the bottom. Under each corner of the parchment paper around the baking sheet, pipe a tiny bit of choux paste (the dough acts as a glue and keeps the paper in place as you pipe).
