Recently I got some hazelnuts and walnuts to snack on, but I got too many. What interesting things can I do with them before they go bad?
A great idea is to make nut butter. Mix it with chocolate--and you've got Nutella!
As already suggested, the best thing to do is to freeze the nuts until you find a use for them. That said, my absolute favorite use for hazelnuts is the following family recipe.
Cake: 8 egg whites, 28 dkg powdered sugar, 28 dkg hazelnut-flour. Preheat oven to 325°F. Thoroughly grease a rectangular cake pan with at least 1 tablespoon unsalted butter. Do not dust with flour! Whip the egg whites until stiff. Continue whipping while adding the sugar, scraping down the bowl occasionally. Gently fold in the nut meal. Spread into prepared pan. Get rid of any air bubbles with your preferred method (whacking against the counter a few times, for instance). Bake until the top springs back and the sides pull away from the pan, about 30 minutes. Cool in pan for about 10 minutes, then turn out onto a wire rack and cool thoroughly.
Frosting: 8 egg yolks, 2 or 3 heaping tablespoons dutch-processed cocoa, 5 tablespoons powdered sugar, 5 tablespoons water, 2 sticks (1 cup) unsalted butter. Combine everything except the butter in the top of a double boiler and cook over barely-simmering water, stirring pretty much constantly, until thick and sticky. This will take a while; enlist
slave labor help if available. Let the chocolate cool completely, then whip the butter and combine it with the chocolate.
Trim off the edges of the cake, then cut it in half lengthwise to make your two layers. Fill, ice, and decorate with the frosting. Chill before serving; cut into relatively thin slices with a warmed knife. (Oh, and the rule is, if anyone so much as mentions a diet, they don't get any.)
 Hazelnut flour or meal: choose your favorite method to roast & blanch or blanch & roast the hazelnuts, then grind (or rather, grate) with a nut grinder. Don't attempt to use a food processor or any other high-speed mechanical device for the grinding, because you'll end up with nut butter instead.
Roast & blanch: the traditional method, whereby you roast the nuts (in the oven or on the stovetop) until the paper skins start popping off, then use a kitchen towel to rub them clean. Well, relatively so.
Blanch & roast: boil water with a couple spoonfuls of baking soda in a large pot, dump in the nuts, bring back to a boil while watching like a hawk because it will foam over, cook for no more than a minute, drain and rinse, and continue rinsing while you rub off the softened skins - kind of like blanching almonds. (Don't bother saving the blanching liquid - despite its amazing color, it doesn't really work as a dye.) When clean, let dry, then roast until golden brown and fragrant.
With hazelnuts, I usually end up making cookies. I've been doing double-chocolate chip with hazelnuts and cherries, but they're good with almost anything that includes chocolate.
I make a tomato salad with blue cheese and candied pecans, and it would probably work well with walnuts as well. 2 pints of cherry tomatoes, cut in half, and mixed with some salt and sugar and left to drain for half an hour or so. The dressing is half a cup of the juice drained from the tomatoes, dijon mustard, honey, cider vinegar, and shallot, all cooked down until it's thick. Let the dressing cool once it's done, then toss it with the tomatoes, blue cheese, the pecans, and some fresh tarragon.