Rhubarb, apple and brown butter pistachio frangipane upside-down cake

• 290g cultured butter
• 8 small apples
• 1 bunch rhubarb
• 0.5 cup packed coconut sugar
• 1.5 tsp Celtic sea salt
• 2 tbsp water
• 110g freshly shelled pistachios
• 60g buckwheat flour
• 40g coconut flour
• 5 tbsp brown caster sugar
• 1.5 tsp ground cinnamon
• 1 tsp baking powder
• 1 tsp freshly grated nutmeg
• 3 duck eggs
• 1 scraped vanilla seed pod

Step 1
I used a copper tarte Tatin pan, however you can substitute with an oven-safe 25cm diameter high sauté pan or cast iron skillet.

Step 2
Make the brown butter in the pan you will be making the cake in.

Step 3
LEAVE!

Step 4
Add 190 grams of cultured butter into the pan on low-medium heat, swirl to evenly coat the pan and using a spatula, scrape down the sides as it starts to bubble.

Step 5
Turn off the heat and remove into a medium mixing bowl.

Step 6
Cool and set aside.

Step 7
Peel and core.

Step 8
Into the pan place 90g of cultured butter on medium heat, then place the apples face down until evenly brown – depending on the apple size and variety, approximately five to seven minutes.

Step 9
Flip and keep on the heat for another three to five minutes.

Step 10
Remove to cool in a bowl and set aside.

Step 11
Cook them in the same pan that you browned the apples, making sure there is still butter left.

Step 12
Arrange the rhubarb so it covers the entire surface nicely.

Step 13
Remove them to cool into the bowl with the apples.

Step 14
In the same pan, on low heat, add the packed organic coconut sugar, half a teaspoon of sea salt and two tablespoons of water, stirring until you’ve made a thick caramel.

Step 15
Let it cool and set aside.

Step 16
Pulse the freshly shelled pistachio with buckwheat flour, baking powder, coconut flour, brown caster sugar, ground cinnamon, freshly grated nutmeg, one teaspoon of sea salt and blend until well incorporated.

Step 17
Into the brown butter from the first step, beat in with a balloon whisk – one at a time – the duck eggs or hen’s eggs and one scraped vanilla seed pod.

Step 18
Continue to beat until it’s all well blended and looks smooth.

Step 19
Add the dry flour mix and fold gently.

Step 20
Into the pan with the caramel, lovingly arrange first the semi-cooked rhubarb, then the apples, evenly around the pan.

Step 21
Scrape the batter mix around the pan so that it coats the apples evenly and smooth the top of the cake.

Step 22
Bake at 175°C for one hour, rotating the cake at 30 minutes to get an even colour.

Step 23
At the one-hour mark, turn off the gas and leave the cake in the oven for another 10 minutes.

Step 24
Take it out of the oven and cool for another 20 minutes.

Step 25
Turn on to a cake plate.