Collecting the hourly energy prices via a service in the EnergyZero or easyEnergy integration and using them in an ApexCharts card in your dashboard.

hourly_price_charts.yaml

- type: custom:apexcharts-card
  graph_span: 1d
  header:
    show: true
    title: Electriciteitsprijzen Vandaag (€/kwh)
  span:
    start: day
  now:
    show: true
    label: Now
  yaxis:
    - id: price
      decimals: 2
      apex_config:
        tickAmount: 5
  series:
    - entity: sensor.energy_prices_today
      name: Price this hour
      yaxis_id: price
      data_generator: |
        return entity.attributes.prices.map((entry) => {
          return [new Date(entry.timestamp).getTime(), entry.price];
        });
      type: column
      show:
        extremas: true
      opacity: 0.8
      float_precision: 2

price_template_sensors.yaml

---
# Today - Hourly energy prices
template:
  - trigger:
      - platform: homeassistant
        event: start
      - platform: time_pattern
        hours: "*"
    action:
      - service: energyzero.get_energy_prices
        response_variable: response
        data:
          config_entry: PUT_HERE_YOURS
          incl_vat: True
    sensor:
      - name: Energy prices - Today
        device_class: timestamp
        state: "{{ now() }}"
        attributes:
          prices: '{{ response.prices }}'

  # Tomorrow - Hourly energy prices
  - trigger:
      - platform: homeassistant
        event: start
      - platform: template
        value_template: "{{ now() > today_at('14:00') and now().minute == 0 }}"
    action:
      - service: energyzero.get_energy_prices
        response_variable: response
        data:
          config_entry: PUT_HERE_YOURS
          start: "{{ now() + timedelta(days=1) }}"
          end: "{{ now() + timedelta(days=1) }}"
          incl_vat: True
    sensor:
      - name: Energy prices - Tomorrow
        device_class: timestamp
        state: "{{ now() + timedelta(days=1) }}"
        attributes:
          prices: '{{ response.prices }}'

@klaasnicolaas i am sorry do you mean i need to add.
hourly_price_charts.yaml and price_template_sensors.yaml

So just copy paste in to configuration.yaml.

Only the YAML of price_template_sensors.yaml to get the 2 trigger template sensors in Home Assistant. You use the apex code snippet where you created your dashboard in YAML.

Side note: everyone uses YAML differently in their Home Assistant instance, without context (how you organize your config) it's impossible to give advice on where to put the code snippets and I assume that people know where you should place these.

Didn't work: defining the template sensor under Settings > Devices & Services > Helpers
Keep getting error "response is undefined"

What works: copy/pasting the template sensor code into configuration.yaml