SIN HORNO SIN HARINA DE TRIGO SIN AZÚCAR REFINADA PAN FÁCIL Y SALUDABLE

4 eggs (241 g), separated by yolks 1/4 cup brown sugar (50 g or 5 tablespoons) 1/2 cup olive oil (120 ml) 200 g unsweetened natural yogurt, sour cream, or cream cheese at room temperature 1 lemon, grated zest 5 g baking powder (1/2 tablespoon) 180 g rice flour (a little less than a cup) for caramelized walnuts 2/3 cup water (160 ml) 4 g cocoa powder (approximately 1 tablespoon) 6 g cornstarch (approximately 1/2 tablespoon) 30 g grated piloncillo, panela (brown sugar), panocha (panocha), zest, or raspadura (scraping sugar) 90 g walnuts