In a medium bowl, add the strawberries, thyme and agave. Mix to combine and set aside.
Preheat oven to 325 degrees. Line a loaf pan with parchment paper.
In a small bowl, whisk together the flour and baking powder. Set aside.
In the bowl of a standing mixer, beat the butter and lemon zest on medium speed until smooth, about 2 minutes.
Slowly add the sugar, scraping down the sides of the bowl, and continue beating for 3 minutes.
Add the eggs one at a time, beating well after each addition.
Add the buttermilk and mix until combined.
Reduce speed to LOW and slowly add the flour mixture, scraping down the sides and beating until smooth. Transfer the batter to the lined loaf pan.
Using a fork, mash the strawberry mixture until it’s a lumpy puree.
Add the puree to the top of the cake batter. Using a knife, swirl the puree through the cake batter until well incorporated.
Bake for 55 minutes or until a toothpick inserted in the middle comes out clean. Allow to cool for 10 minutes before serving.