For the Cake: Preheat oven to 350°F. Brush a 10-to-15-cup Bundt pan with shortening; dust with flour, tapping out excess.
In a small bowl, stir together milk and orange juice. In another bowl, whisk together flour, baking powder, baking soda, salt, and cardamom to thoroughly combine.
Beat butter with sugar and orange zest on medium‐high speed until pale and fluffy, 2 to 3 minutes. Beat in eggs, one at a time, then vanilla. Reduce speed to medium‐low and beat in flour mixture, alternating with milk mixture, each in two additions. Transfer batter to prepared pan; smooth top with a spatula.
In a high speed blender or food processor, grind the pistachios into a fine meal. Add flour and salt (only if nuts are not salted). Add oil, maple syrup, and lemon zest, and quickly pulse until you’ve got a sand-like texture. Sprinkle evenly over the top of the batter.
Bake until cake is puffed slightly and a wooden skewer inserted into center comes out clean, about 45-60 minutes. Let cool in pan on a wire rack for maximum of 15 minutes.