This basic brownie recipe is great, but don't be afraid to make it your own. Add chopped nuts (walnuts and pecans are great), chocolate or peanut butter morsels, dried fruit, or whatever suits you!
Grease a 9x13 baking pan and dust lightly with flour.
Using a saucepan, melt the chocolate and butter over low heat, stirring frequently. Really keep an eye on it to prevent it from scorching. When fully melted, remove from the heat and allow to cool.
Combine the eggs, vanilla extract, salt, and sugar in a large mixing bowl and beat with an electric mixer for 8-10 minutes. Gently stir in the chocolate mixture, then add the flour, stirring until just blended.
Spread the batter evenly in the pan and bake for 23-25 minutes (center should still be moist).