- Preheat the oven to 325 degrees with a rack in the lower third of the oven. Line an 8x8-inch metal baking pan across the bottom and up two opposite sides with parchment paper.
- If using whole almonds, add them to a food process with the rice flour and pulse until the nuts are finely ground. If using almond flour, mix it with the rice flour. Set aside.
- Place the chocolate, butter and salt in the top of a large double boiler over barely simmering water. Stir frequently until the chocolate is melted and the mixture is smooth. Remove the bowl and let cool for 5 minutes. Stir in the sugar and vanilla. Stir in the eggs one at a time. Add the almond and rice flour mixture and stir until moistened, and then mix briskly about 40 strokes. Stir in the walnuts or pecans if using.
- Scrape the batter into the prepared pan and spread it evenly. Bake 20 to 25 minutes or until the brownies are slightly puffed all over and a toothpick inserted into the center comes out moist but clean. Cool the pan on a rack. Run a knife along the unlined sides of the pan to detach the brownies. Lift the edges of the parchment paper to remove the brownies. Cut into squares.