'Healthy' rhubarb meringue pie

Ingredients

• 50 gram (lactose free) butter (lukewarm) + extra
• 125 ml (lactose free) milk (lukewarm)
• 250 gram spelt flour + extra
• half sachet dry yeast or use fresh yeast
• 50 gram coconut blossom sugar
• 600 gram rhubarb
• splash of water
• 200 gram coconut blossom sugar
• 1 vanilla pod
• optional: agar or cornstarch for thickening the rhubarb compote
• optional: about 200 gram apple compote (drain very well!)
• 4 egg whites
• 100 gram coconut blossom sugar
• pinch of salt