Preheat the oven to 400 degrees.
For the cookies: Place the nuts on a small baking sheet and place in the oven. Roast until golden, about 4 to 6 minutes. Remove from the oven and cool. Using a small food processor, grind the nuts.
Cream the butter and sugar in the bowl of an electric mixer fitted with a paddle on medium speed, scraping down the sides of the bowl as necessary. Cream the mixture until it is smooth and fluffy. Add the egg yolks 1 at a time, mixing in between each addition. Scrape down the sides of the bowl. Beat for 1 minute and add the vanilla.
Combine the flour, ground nuts and salt in a medium-size mixing bowl and mix well. Add to the butter mixture and mix on low speed until it is fully incorporated. Increase the speed to medium and mix until the batter is thick and creamy, about 2 minutes. Scrape down the sides of the bowl and paddle.
Generously dust a large sheet of parchment or waxed paper with flour. Spoon the dough down the center of the paper, fold the paper tightly over the dough, and roll into a cylinder about 3 inches in diameter and 12 to 14 inches long. Refrigerate for 8 hours.
Reduce the heat of the oven to 350 degrees.
Line a baking sheet with parchment or waxed paper. Remove the dough from the refrigerator and peel away the paper. Using a sharp knife, cut the dough crosswise into 1/2-inch thick slices. Place them on the baking sheet about 2 inches apart. Bake until lightly golden, about 20 minutes.
Remove the cookies from the oven and let cool completely in the pan. Remove the cookies from the pan using a spatula or thin knife. Repeat the process until all of the dough is used. (Yields 2 1/2 dozen cookies)
For the ice cream: In a nonreactive saucepan, combine the half-and-half, powdered wattleseed, vanilla, wattleseed extract, sugar, and salt, over medium heat. Bring the cream to the boiling point and scald it. Remove from the heat. Beat the egg yolks in a bowl. Add the cream mixture, about 1/4 cup at a time, to the beaten eggs, whisking in between each addition, until all is used.
Pour the mixture into a saucepan, and cook, stirring, over medium heat, for 2 to 3 minutes, or until the mixture becomes thick enough to coat the back of a spoon. Strain the mixture through a fine mesh sieve. Pour the filling into the ice cream machine and follow the manufacturer's instructions for churning time. (Yields about 1/2 gallon)
Spoon the ice cream into serving dishes and serve with the cookies.
This recipe yields ?? servings.