Preheat oven to 325ºF (160ºC).
In bowl, combine breadcrumbs and walnuts; stir in butter and walnut oil, until well moistened. Press onto bottom of greased 8 1/2-inch (2.25 L) spring form pan. Centre pan on large square of foil; press foil to side of pan. Bake in centre of oven until golden, about 20 minutes. Let cool.
In large bowl, beat cream cheese with mustard until fluffy. Beat in eggs, 1 at a time, beating well after each addition. Stir in garlic, basil, thyme, sage and pepper. Blend in sour cream. Blend in Stilton cheese. Pour over base.
Set pan in larger pan; pour in enough hot water to come 1-inch (2.5 cm) up sides. Bake in centre of oven for about 1 hour or until set around edge and centre is still jiggly. Turn off oven; let stand in oven for 1 hour.
Transfer spring form pan to rack and remove foil; let cool completely. Cover with plastic wrap and refrigerate for at least 4 hours or until chilled. (Make-ahead: Refrigerate for up to 2 days or freeze in airtight container for up to 2 weeks.)
Bring to room temperature before serving. Garnish outside edge with coarsely chopped toasted walnuts.