Preheat your oven to 350°F (175°C). Line an oval or rectangular baking sheet with parchment paper and set aside.
In a mixing bowl, whisk together eggs and sugar until the mixture turns pale and slightly thickened, about 3-4 minutes.
Add in the oil, milk, vanilla extract, and whisk until smooth.
Sift together the cocoa powder and flour, then gently fold into the wet mixture until just combined, creating a smooth batter.
Pour the batter evenly onto the prepared baking sheet and spread it out into a thin layer with a spatula.
Bake for 12-15 minutes, or until the cake is set but still soft. Remove from oven and cover with a clean towel or parchment paper, then gently roll the warm cake from one end to create a tight roll. Let it cool completely.
While the cake cools, prepare the peanut butter filling by mixing the peanut butter with powdered sugar until smooth and creamy.
Pick apart the cooled cake gently, unrolling it carefully. Spread the peanut butter mixture evenly over the unrolled cake.
Re-roll the cake tightly, sealing the edges. Place the rolled cake in the refrigerator to firm up for about 15 minutes.
Heat the heavy cream until just simmering, then pour over the chopped dark chocolate. Let sit for 2-3 minutes, then stir until shiny and smooth to make the ganache.
Unwrap the chilled cake and place on a serving plate, then pour the chocolate ganache over the top, allowing it to drip down the sides beautifully.
Sprinkle crushed pretzels evenly over the ganache and finish with a light sprinkle of coarse sea salt for added flavor and crunch.
Slice the cake to reveal the spiral of peanut butter inside the rich, chocolate coating. Serve immediately or refrigerate until ready to enjoy.
