Combine crust ingredients and press into 8" tart pan. Bake 350*, 15 minutes or till light brown.
Bring cream to simmer, then pour over dark chocolate and let sit for a 3 minutes.
Add vanilla and stir till well blended. Spread a thin layer on baked crust, (don't use all ganache save some for topping later). Place in freezer while preparing mousse.
Using an electric mixer, beat peanut butter, sugar and course salt till well blended.
With mixer running carefully add 1/4 cp. heavy cream. Add another 1/4 cp. heavy cream and beat just till blended.
In a separate bowl beat remaining 1/2 cp. heavy cream, sugar and vanilla till peaks form. Fold into peanut butter mixture in three additions. Spread Mousse on ganache layered crust and top with pecan pieces and drizzle ganache over top. You can eat at once or freeze till ready to use.