Preheat your oven to 250°F (120°C) and line a large baking sheet with parchment paper or a silicone baking mat for easy cleanup.

In a large mixing bowl, combine the Crispix cereal and pecan halves, then set aside.

In a medium saucepan, combine the brown sugar, corn syrup, and butter. Cook over medium heat, stirring constantly, until the mixture comes to a boil. Let it boil for 2 minutes, then remove from heat. Stir in the baking soda and vanilla extract. The mixture will bubble up slightly—this is normal and helps create the light, crispy coating.

Pour the praline mixture over the cereal and nuts in the bowl. Gently stir with a spatula to coat everything evenly.

Spread the coated mixture evenly onto the prepared baking sheet. Bake for 1 hour, stirring every 15 minutes to ensure even coating and prevent sticking.

Remove from the oven and let the praline crunch cool completely on the baking sheet. Once cooled, break into bite-sized pieces and transfer to an airtight container for storage.