controller.php

<?php

class FormController
{
	public function formAction()
	{
		$form = $this->createFormBuilder()
			->add('something_at', 'datetime', [
				'date_widget' => 'single_text',
				'time_widget' => 'single_text',
			])
			->getForm();

		return $this->render('form.html.twig', [
			'form' => $form->createView(),
		]);
	}
}

form.html.twig

{# Musimy rozszerzyć cokolwiek, żeby nie próbował drukować bloków:
	https://github.com/symfony/symfony-docs/issues/5475 #}
{% extends '::empty.html.twig' %}

{% form_theme form with ['form_div_layout.html.twig', _self] %}

{# wszystkie rządki mają mieć klasę "row", więc nadpisujemy domyślną definicję #}
{%- block form_row -%}
	<div class="row">
		{{- form_label(form) -}}
		{{- form_errors(form) -}}
		{{- form_widget(form) -}}
	</div>
{%- endblock form_row -%}

{%- block _form_something_at_date_widget -%}
	<div class="large-6 columns">
		{% set attr = {
			'class': 'date_field',
			'data-abide-validator': 'date_from_validator',
			'data-datepicker': '1'
		} %}
		{{- block('form_widget') -}}
	</div>
{%- endblock -%}

{%- block _form_something_at_time_widget -%}
	<div class="large-6 columns">
		{% set attr = {
			'class': 'time_field',
			'data-abide-validator': 'time_validator'
		} %}
		{{- block('form_widget') -}}
	</div>
{%- endblock -%}

{%- block content -%}
	{{- form(form) -}}
{%- endblock -%}

result.html

<form name="form" method="post" action="">
	<div id="form">
		<div class="row">
			<label class="required">Something at</label>
			<div id="form_something_at">
				<div class="large-6 columns">
					<input type="date" id="form_something_at_date" name="form[something_at][date]" required="required" class="date_field" data-abide-validator="date_from_validator" data-datepicker="1" />
				</div>
				<div class="large-6 columns">
					<input type="time" id="form_something_at_time" name="form[something_at][time]" required="required" class="time_field" data-abide-validator="time_validator" />
				</div>
			</div>
		</div>
		<input type="hidden" id="form__token" name="form[_token]" value="7CaXdlHdx0nGdEaZsAAWr3TpkfLJ6Nqh6CdpFizD2NY" />
	</div>
</form>