Heat the oven to 350ºF and prepare a 9x13 inch pan with cooking spray (or with foil or parchment paper, leaving enough hanging over so you can pull it out to cut).
Toast the walnuts (use a pat of butter in a skillet and toast until they are very nutty).
Using a mixer, mix the butter and brown sugar. Add in the flour and salt and mix until together. Add the toasted walnuts and combine.
Press the crust into the pan and bake for 25 minutes.
If you don't know how to brown butter, I put it into a saucepan or small skillet and cook on medium heat, stirring for around 5-8 minutes until it starts to get brown flakes and has a rich, nutty smell.
While the crust is baking, you can make the topping - after you brown the butter, this takes less than 10 minutes, so I like waiting until there is less than 10 minutes left in the baking time to work on this so I can pour it directly on top of the crust when it is done, and it doesn't have time to set on its own.
After browning the butter (browning is optional, you could just use butter), add the brown sugar, honey, maple syrup, cinnamon, heavy cream, and salt into the saucepan and stir over medium heat. Continue to stir until it starts to simmer. Do not simmer (bubble up) for more than 1 minute or the topping may become too hard. Remove from the heat and the pecans and vanilla and combine.
Remove the crust from the oven and immediately pour the pecan over the crust, spreading it and smoothing it out to cover the entire crust.
Return the pan to the oven and bake for 15 minutes.
Take the pan out and allow to completely cool before cutting. We put these in the fridge overnight and they firmed up very nicely for cutting into squares.
