1. Prepare the Crust:

1. Sift together almond flour and 180g powdered sugar into a large bowl. Discard any large pieces.
2. In a separate clean, dry bowl, beat egg whites and cream of tartar on medium speed until foamy. Gradually add granulated sugar, then increase speed to high and whip until stiff, glossy peaks form. Mix in vanilla.
3. Gently fold the dry ingredients into the meringue in three batches until the batter flows like lava and a figure-8 can be drawn without the ribbon breaking.
4. Transfer batter to a piping bag fitted with a round tip. Pipe 1-inch circles onto parchment-lined baking sheets. Firmly tap the sheets on the counter to release air bubbles.
5. Let the macarons rest at room temperature for 30-60 minutes until a skin forms and they are no longer sticky to the touch.
6. Preheat oven to 300°F (150°C). Bake for 15-18 minutes, rotating the tray halfway. Let cool completely on the baking sheet before filling.
7. For the buttercream, beat butter until light and fluffy. Gradually add powdered sugar, then vanilla and cream. Beat until smooth. Pipe onto the flat side of a macaron shell and sandwich with another.